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Enable drop_tracking_mir by default.

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This commit is contained in:
Camille GILLOT 2023-01-28 12:56:04 +00:00
parent a626caaad9
commit 286502c9ed
29 changed files with 114 additions and 2513 deletions
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9
compiler/rustc_hir_analysis/src/check/check.rs
View file

@ -1579,13 +1579,7 @@ fn opaque_type_cycle_error(
label_match(capture.place.ty(), capture.get_path_span(tcx));
}
// Label any generator locals that capture the opaque
for interior_ty in
typeck_results.generator_interior_types.as_ref().skip_binder()
{
label_match(interior_ty.ty, interior_ty.span);
}
if tcx.sess.opts.unstable_opts.drop_tracking_mir
&& let DefKind::Generator = tcx.def_kind(closure_def_id)
if let DefKind::Generator = tcx.def_kind(closure_def_id)
&& let Some(generator_layout) = tcx.mir_generator_witnesses(closure_def_id)
{
for interior_ty in &generator_layout.field_tys {
@ -1603,7 +1597,6 @@ fn opaque_type_cycle_error(
}
pub(super) fn check_generator_obligations(tcx: TyCtxt<'_>, def_id: LocalDefId) {
debug_assert!(tcx.sess.opts.unstable_opts.drop_tracking_mir);
debug_assert!(matches!(tcx.def_kind(def_id), DefKind::Generator));
let typeck = tcx.typeck(def_id);

18
compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
View file

@ -510,25 +510,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
pub(in super::super) fn resolve_generator_interiors(&self, def_id: DefId) {
if self.tcx.sess.opts.unstable_opts.drop_tracking_mir {
self.save_generator_interior_predicates(def_id);
return;
}
self.select_obligations_where_possible(|_| {});
let mut generators = self.deferred_generator_interiors.borrow_mut();
for (generator_def_id, body_id, interior, kind) in generators.drain(..) {
crate::generator_interior::resolve_interior(
self,
def_id,
generator_def_id,
body_id,
interior,
kind,
);
self.select_obligations_where_possible(|_| {});
}
}
/// Unify the inference variables corresponding to generator witnesses, and save all the

601
compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs
View file

@ -1,601 +0,0 @@
use super::{
for_each_consumable, record_consumed_borrow::ConsumedAndBorrowedPlaces, DropRangesBuilder,
NodeInfo, PostOrderId, TrackedValue, TrackedValueIndex,
};
use hir::{
intravisit::{self, Visitor},
Body, Expr, ExprKind, Guard, HirId, LoopIdError,
};
use rustc_data_structures::unord::{UnordMap, UnordSet};
use rustc_hir as hir;
use rustc_index::IndexVec;
use rustc_infer::infer::InferCtxt;
use rustc_middle::{
hir::map::Map,
ty::{ParamEnv, TyCtxt, TypeVisitableExt, TypeckResults},
};
use std::mem::swap;
/// Traverses the body to find the control flow graph and locations for the
/// relevant places are dropped or reinitialized.
///
/// The resulting structure still needs to be iterated to a fixed point, which
/// can be done with propagate_to_fixpoint in cfg_propagate.
pub(super) fn build_control_flow_graph<'tcx>(
infcx: &InferCtxt<'tcx>,
typeck_results: &TypeckResults<'tcx>,
param_env: ParamEnv<'tcx>,
consumed_borrowed_places: ConsumedAndBorrowedPlaces,
body: &'tcx Body<'tcx>,
num_exprs: usize,
) -> (DropRangesBuilder, UnordSet<HirId>) {
let mut drop_range_visitor = DropRangeVisitor::new(
infcx,
typeck_results,
param_env,
consumed_borrowed_places,
num_exprs,
);
intravisit::walk_body(&mut drop_range_visitor, body);
drop_range_visitor.drop_ranges.process_deferred_edges();
if let Some(filename) = &infcx.tcx.sess.opts.unstable_opts.dump_drop_tracking_cfg {
super::cfg_visualize::write_graph_to_file(
&drop_range_visitor.drop_ranges,
filename,
infcx.tcx,
);
}
(drop_range_visitor.drop_ranges, drop_range_visitor.places.borrowed_temporaries)
}
/// This struct is used to gather the information for `DropRanges` to determine the regions of the
/// HIR tree for which a value is dropped.
///
/// We are interested in points where a variables is dropped or initialized, and the control flow
/// of the code. We identify locations in code by their post-order traversal index, so it is
/// important for this traversal to match that in `RegionResolutionVisitor` and `InteriorVisitor`.
///
/// We make several simplifying assumptions, with the goal of being more conservative than
/// necessary rather than less conservative (since being less conservative is unsound, but more
/// conservative is still safe). These assumptions are:
///
/// 1. Moving a variable `a` counts as a move of the whole variable.
/// 2. Moving a partial path like `a.b.c` is ignored.
/// 3. Reinitializing through a field (e.g. `a.b.c = 5`) counts as a reinitialization of all of
/// `a`.
///
/// Some examples:
///
/// Rule 1:
/// ```rust
/// let mut a = (vec![0], vec![0]);
/// drop(a);
/// // `a` is not considered initialized.
/// ```
///
/// Rule 2:
/// ```rust
/// let mut a = (vec![0], vec![0]);
/// drop(a.0);
/// drop(a.1);
/// // `a` is still considered initialized.
/// ```
///
/// Rule 3:
/// ```compile_fail,E0382
/// let mut a = (vec![0], vec![0]);
/// drop(a);
/// a.1 = vec![1];
/// // all of `a` is considered initialized
/// ```
struct DropRangeVisitor<'a, 'tcx> {
typeck_results: &'a TypeckResults<'tcx>,
infcx: &'a InferCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
places: ConsumedAndBorrowedPlaces,
drop_ranges: DropRangesBuilder,
expr_index: PostOrderId,
label_stack: Vec<(Option<rustc_ast::Label>, PostOrderId)>,
}
impl<'a, 'tcx> DropRangeVisitor<'a, 'tcx> {
fn new(
infcx: &'a InferCtxt<'tcx>,
typeck_results: &'a TypeckResults<'tcx>,
param_env: ParamEnv<'tcx>,
places: ConsumedAndBorrowedPlaces,
num_exprs: usize,
) -> Self {
debug!("consumed_places: {:?}", places.consumed);
let drop_ranges = DropRangesBuilder::new(
places.consumed.iter().flat_map(|(_, places)| places.iter().cloned()),
infcx.tcx.hir(),
num_exprs,
);
Self {
infcx,
typeck_results,
param_env,
places,
drop_ranges,
expr_index: PostOrderId::from_u32(0),
label_stack: vec![],
}
}
fn tcx(&self) -> TyCtxt<'tcx> {
self.infcx.tcx
}
fn record_drop(&mut self, value: TrackedValue) {
if self.places.borrowed.contains(&value) {
debug!("not marking {:?} as dropped because it is borrowed at some point", value);
} else {
debug!("marking {:?} as dropped at {:?}", value, self.expr_index);
let count = self.expr_index;
self.drop_ranges.drop_at(value, count);
}
}
/// ExprUseVisitor's consume callback doesn't go deep enough for our purposes in all
/// expressions. This method consumes a little deeper into the expression when needed.
fn consume_expr(&mut self, expr: &hir::Expr<'_>) {
debug!("consuming expr {:?}, count={:?}", expr.kind, self.expr_index);
let places = self
.places
.consumed
.get(&expr.hir_id)
.map_or(vec![], |places| places.iter().cloned().collect());
for place in places {
trace!(?place, "consuming place");
for_each_consumable(self.tcx().hir(), place, |value| self.record_drop(value));
}
}
/// Marks an expression as being reinitialized.
///
/// Note that we always approximated on the side of things being more
/// initialized than they actually are, as opposed to less. In cases such
/// as `x.y = ...`, we would consider all of `x` as being initialized
/// instead of just the `y` field.
///
/// This is because it is always safe to consider something initialized
/// even when it is not, but the other way around will cause problems.
///
/// In the future, we will hopefully tighten up these rules to be more
/// precise.
fn reinit_expr(&mut self, expr: &hir::Expr<'_>) {
// Walk the expression to find the base. For example, in an expression
// like `*a[i].x`, we want to find the `a` and mark that as
// reinitialized.
match expr.kind {
ExprKind::Path(hir::QPath::Resolved(
_,
hir::Path { res: hir::def::Res::Local(hir_id), .. },
)) => {
// This is the base case, where we have found an actual named variable.
let location = self.expr_index;
debug!("reinitializing {:?} at {:?}", hir_id, location);
self.drop_ranges.reinit_at(TrackedValue::Variable(*hir_id), location);
}
ExprKind::Field(base, _) => self.reinit_expr(base),
// Most expressions do not refer to something where we need to track
// reinitializations.
//
// Some of these may be interesting in the future
ExprKind::Path(..)
| ExprKind::ConstBlock(..)
| ExprKind::Array(..)
| ExprKind::Call(..)
| ExprKind::MethodCall(..)
| ExprKind::Tup(..)
| ExprKind::Binary(..)
| ExprKind::Unary(..)
| ExprKind::Lit(..)
| ExprKind::Cast(..)
| ExprKind::Type(..)
| ExprKind::DropTemps(..)
| ExprKind::Let(..)
| ExprKind::If(..)
| ExprKind::Loop(..)
| ExprKind::Match(..)
| ExprKind::Closure { .. }
| ExprKind::Block(..)
| ExprKind::Assign(..)
| ExprKind::AssignOp(..)
| ExprKind::Index(..)
| ExprKind::AddrOf(..)
| ExprKind::Break(..)
| ExprKind::Continue(..)
| ExprKind::Ret(..)
| ExprKind::Become(..)
| ExprKind::InlineAsm(..)
| ExprKind::OffsetOf(..)
| ExprKind::Struct(..)
| ExprKind::Repeat(..)
| ExprKind::Yield(..)
| ExprKind::Err(_) => (),
}
}
/// For an expression with an uninhabited return type (e.g. a function that returns !),
/// this adds a self edge to the CFG to model the fact that the function does not
/// return.
fn handle_uninhabited_return(&mut self, expr: &Expr<'tcx>) {
let ty = self.typeck_results.expr_ty(expr);
let ty = self.infcx.resolve_vars_if_possible(ty);
if ty.has_non_region_infer() {
self.tcx()
.sess
.delay_span_bug(expr.span, format!("could not resolve infer vars in `{ty}`"));
return;
}
let ty = self.tcx().erase_regions(ty);
let m = self.tcx().parent_module(expr.hir_id).to_def_id();
if !ty.is_inhabited_from(self.tcx(), m, self.param_env) {
// This function will not return. We model this fact as an infinite loop.
self.drop_ranges.add_control_edge(self.expr_index + 1, self.expr_index + 1);
}
}
/// Map a Destination to an equivalent expression node
///
/// The destination field of a Break or Continue expression can target either an
/// expression or a block. The drop range analysis, however, only deals in
/// expression nodes, so blocks that might be the destination of a Break or Continue
/// will not have a PostOrderId.
///
/// If the destination is an expression, this function will simply return that expression's
/// hir_id. If the destination is a block, this function will return the hir_id of last
/// expression in the block.
fn find_target_expression_from_destination(
&self,
destination: hir::Destination,
) -> Result<HirId, LoopIdError> {
destination.target_id.map(|target| {
let node = self.tcx().hir().get(target);
match node {
hir::Node::Expr(_) => target,
hir::Node::Block(b) => find_last_block_expression(b),
hir::Node::Param(..)
| hir::Node::Item(..)
| hir::Node::ForeignItem(..)
| hir::Node::TraitItem(..)
| hir::Node::ImplItem(..)
| hir::Node::Variant(..)
| hir::Node::Field(..)
| hir::Node::AnonConst(..)
| hir::Node::ConstBlock(..)
| hir::Node::Stmt(..)
| hir::Node::PathSegment(..)
| hir::Node::Ty(..)
| hir::Node::TypeBinding(..)
| hir::Node::TraitRef(..)
| hir::Node::Pat(..)
| hir::Node::PatField(..)
| hir::Node::ExprField(..)
| hir::Node::Arm(..)
| hir::Node::Local(..)
| hir::Node::Ctor(..)
| hir::Node::Lifetime(..)
| hir::Node::GenericParam(..)
| hir::Node::Crate(..)
| hir::Node::Infer(..) => bug!("Unsupported branch target: {:?}", node),
}
})
}
}
fn find_last_block_expression(block: &hir::Block<'_>) -> HirId {
block.expr.map_or_else(
// If there is no tail expression, there will be at least one statement in the
// block because the block contains a break or continue statement.
|| block.stmts.last().unwrap().hir_id,
|expr| expr.hir_id,
)
}
impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> {
fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
let mut reinit = None;
match expr.kind {
ExprKind::Assign(lhs, rhs, _) => {
self.visit_expr(rhs);
self.visit_expr(lhs);
reinit = Some(lhs);
}
ExprKind::If(test, if_true, if_false) => {
self.visit_expr(test);
let fork = self.expr_index;
self.drop_ranges.add_control_edge(fork, self.expr_index + 1);
self.visit_expr(if_true);
let true_end = self.expr_index;
self.drop_ranges.add_control_edge(fork, self.expr_index + 1);
if let Some(if_false) = if_false {
self.visit_expr(if_false);
}
self.drop_ranges.add_control_edge(true_end, self.expr_index + 1);
}
ExprKind::Match(scrutinee, arms, ..) => {
// We walk through the match expression almost like a chain of if expressions.
// Here's a diagram to follow along with:
//
// ┌─┐
// match │A│ {
// ┌───┴─┘
// │
// ┌▼┌───►┌─┐ ┌─┐
// │B│ if │C│ =>│D│,
// └─┘ ├─┴──►└─┴──────┐
// ┌──┘ │
// ┌──┘ │
// │ │
// ┌▼┌───►┌─┐ ┌─┐ │
// │E│ if │F│ =>│G│, │
// └─┘ ├─┴──►└─┴┐ │
// │ │ │
// } ▼ ▼ │
// ┌─┐◄───────────────────┘
// │H│
// └─┘
//
// The order we want is that the scrutinee (A) flows into the first pattern (B),
// which flows into the guard (C). Then the guard either flows into the arm body
// (D) or into the start of the next arm (E). Finally, the body flows to the end
// of the match block (H).
//
// The subsequent arms follow the same ordering. First we go to the pattern, then
// the guard (if present, otherwise it flows straight into the body), then into
// the body and then to the end of the match expression.
//
// The comments below show which edge is being added.
self.visit_expr(scrutinee);
let (guard_exit, arm_end_ids) = arms.iter().fold(
(self.expr_index, vec![]),
|(incoming_edge, mut arm_end_ids), hir::Arm { pat, body, guard, .. }| {
// A -> B, or C -> E
self.drop_ranges.add_control_edge(incoming_edge, self.expr_index + 1);
self.visit_pat(pat);
// B -> C and E -> F are added implicitly due to the traversal order.
match guard {
Some(Guard::If(expr)) => self.visit_expr(expr),
Some(Guard::IfLet(let_expr)) => {
self.visit_let_expr(let_expr);
}
None => (),
}
// Likewise, C -> D and F -> G are added implicitly.
// Save C, F, so we can add the other outgoing edge.
let to_next_arm = self.expr_index;
// The default edge does not get added since we also have an explicit edge,
// so we also need to add an edge to the next node as well.
//
// This adds C -> D, F -> G
self.drop_ranges.add_control_edge(self.expr_index, self.expr_index + 1);
self.visit_expr(body);
// Save the end of the body so we can add the exit edge once we know where
// the exit is.
arm_end_ids.push(self.expr_index);
// Pass C to the next iteration, as well as vec![D]
//
// On the last round through, we pass F and vec![D, G] so that we can
// add all the exit edges.
(to_next_arm, arm_end_ids)
},
);
// F -> H
self.drop_ranges.add_control_edge(guard_exit, self.expr_index + 1);
arm_end_ids.into_iter().for_each(|arm_end| {
// D -> H, G -> H
self.drop_ranges.add_control_edge(arm_end, self.expr_index + 1)
});
}
ExprKind::Loop(body, label, ..) => {
let loop_begin = self.expr_index + 1;
self.label_stack.push((label, loop_begin));
if body.stmts.is_empty() && body.expr.is_none() {
// For empty loops we won't have updated self.expr_index after visiting the
// body, meaning we'd get an edge from expr_index to expr_index + 1, but
// instead we want an edge from expr_index + 1 to expr_index + 1.
self.drop_ranges.add_control_edge(loop_begin, loop_begin);
} else {
self.visit_block(body);
self.drop_ranges.add_control_edge(self.expr_index, loop_begin);
}
self.label_stack.pop();
}
// Find the loop entry by searching through the label stack for either the last entry
// (if label is none), or the first entry where the label matches this one. The Loop
// case maintains this stack mapping labels to the PostOrderId for the loop entry.
ExprKind::Continue(hir::Destination { label, .. }, ..) => self
.label_stack
.iter()
.rev()
.find(|(loop_label, _)| label.is_none() || *loop_label == label)
.map_or((), |(_, target)| {
self.drop_ranges.add_control_edge(self.expr_index, *target)
}),
ExprKind::Break(destination, value) => {
// destination either points to an expression or to a block. We use
// find_target_expression_from_destination to use the last expression of the block
// if destination points to a block.
//
// We add an edge to the hir_id of the expression/block we are breaking out of, and
// then in process_deferred_edges we will map this hir_id to its PostOrderId, which
// will refer to the end of the block due to the post order traversal.
if let Ok(target) = self.find_target_expression_from_destination(destination) {
self.drop_ranges.add_control_edge_hir_id(self.expr_index, target)
}
if let Some(value) = value {
self.visit_expr(value);
}
}
ExprKind::Become(_call) => bug!("encountered a tail-call inside a generator"),
ExprKind::Call(f, args) => {
self.visit_expr(f);
for arg in args {
self.visit_expr(arg);
}
self.handle_uninhabited_return(expr);
}
ExprKind::MethodCall(_, receiver, exprs, _) => {
self.visit_expr(receiver);
for expr in exprs {
self.visit_expr(expr);
}
self.handle_uninhabited_return(expr);
}
ExprKind::AddrOf(..)
| ExprKind::Array(..)
// FIXME(eholk): We probably need special handling for AssignOps. The ScopeTree builder
// in region.rs runs both lhs then rhs and rhs then lhs and then sets all yields to be
// the latest they show up in either traversal. With the older scope-based
// approximation, this was fine, but it's probably not right now. What we probably want
// to do instead is still run both orders, but consider anything that showed up as a
// yield in either order.
| ExprKind::AssignOp(..)
| ExprKind::Binary(..)
| ExprKind::Block(..)
| ExprKind::Cast(..)
| ExprKind::Closure { .. }
| ExprKind::ConstBlock(..)
| ExprKind::DropTemps(..)
| ExprKind::Err(_)
| ExprKind::Field(..)
| ExprKind::Index(..)
| ExprKind::InlineAsm(..)
| ExprKind::OffsetOf(..)
| ExprKind::Let(..)
| ExprKind::Lit(..)
| ExprKind::Path(..)
| ExprKind::Repeat(..)
| ExprKind::Ret(..)
| ExprKind::Struct(..)
| ExprKind::Tup(..)
| ExprKind::Type(..)
| ExprKind::Unary(..)
| ExprKind::Yield(..) => intravisit::walk_expr(self, expr),
}
self.expr_index = self.expr_index + 1;
self.drop_ranges.add_node_mapping(expr.hir_id, self.expr_index);
self.consume_expr(expr);
if let Some(expr) = reinit {
self.reinit_expr(expr);
}
}
fn visit_pat(&mut self, pat: &'tcx hir::Pat<'tcx>) {
intravisit::walk_pat(self, pat);
// Increment expr_count here to match what InteriorVisitor expects.
self.expr_index = self.expr_index + 1;
// Save a node mapping to get better CFG visualization
self.drop_ranges.add_node_mapping(pat.hir_id, self.expr_index);
}
}
impl DropRangesBuilder {
fn new(
tracked_values: impl Iterator<Item = TrackedValue>,
hir: Map<'_>,
num_exprs: usize,
) -> Self {
let mut tracked_value_map = UnordMap::<_, TrackedValueIndex>::default();
let mut next = <_>::from(0u32);
for value in tracked_values {
for_each_consumable(hir, value, |value| {
if let std::collections::hash_map::Entry::Vacant(e) = tracked_value_map.entry(value)
{
e.insert(next);
next = next + 1;
}
});
}
debug!("hir_id_map: {:#?}", tracked_value_map);
let num_values = tracked_value_map.len();
Self {
tracked_value_map,
nodes: IndexVec::from_fn_n(|_| NodeInfo::new(num_values), num_exprs + 1),
deferred_edges: <_>::default(),
post_order_map: <_>::default(),
}
}
fn tracked_value_index(&self, tracked_value: TrackedValue) -> TrackedValueIndex {
*self.tracked_value_map.get(&tracked_value).unwrap()
}
/// Adds an entry in the mapping from HirIds to PostOrderIds
///
/// Needed so that `add_control_edge_hir_id` can work.
fn add_node_mapping(&mut self, node_hir_id: HirId, post_order_id: PostOrderId) {
self.post_order_map.insert(node_hir_id, post_order_id);
}
/// Like add_control_edge, but uses a hir_id as the target.
///
/// This can be used for branches where we do not know the PostOrderId of the target yet,
/// such as when handling `break` or `continue`.
fn add_control_edge_hir_id(&mut self, from: PostOrderId, to: HirId) {
self.deferred_edges.push((from, to));
}
fn drop_at(&mut self, value: TrackedValue, location: PostOrderId) {
let value = self.tracked_value_index(value);
self.node_mut(location).drops.push(value);
}
fn reinit_at(&mut self, value: TrackedValue, location: PostOrderId) {
let value = match self.tracked_value_map.get(&value) {
Some(value) => *value,
// If there's no value, this is never consumed and therefore is never dropped. We can
// ignore this.
None => return,
};
self.node_mut(location).reinits.push(value);
}
/// Looks up PostOrderId for any control edges added by HirId and adds a proper edge for them.
///
/// Should be called after visiting the HIR but before solving the control flow, otherwise some
/// edges will be missed.
fn process_deferred_edges(&mut self) {
trace!("processing deferred edges. post_order_map={:#?}", self.post_order_map);
let mut edges = vec![];
swap(&mut edges, &mut self.deferred_edges);
edges.into_iter().for_each(|(from, to)| {
trace!("Adding deferred edge from {:?} to {:?}", from, to);
let to = *self.post_order_map.get(&to).expect("Expression ID not found");
trace!("target edge PostOrderId={:?}", to);
self.add_control_edge(from, to)
});
}
}

92
compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_propagate.rs
View file

@ -1,92 +0,0 @@
use super::{DropRangesBuilder, PostOrderId};
use rustc_index::{bit_set::BitSet, IndexVec};
use std::collections::BTreeMap;
impl DropRangesBuilder {
pub fn propagate_to_fixpoint(&mut self) {
trace!("before fixpoint: {:#?}", self);
let preds = self.compute_predecessors();
trace!("predecessors: {:#?}", preds.iter_enumerated().collect::<BTreeMap<_, _>>());
let mut new_state = BitSet::new_empty(self.num_values());
let mut changed_nodes = BitSet::new_empty(self.nodes.len());
let mut unchanged_mask = BitSet::new_filled(self.nodes.len());
changed_nodes.insert(0u32.into());
let mut propagate = || {
let mut changed = false;
unchanged_mask.insert_all();
for id in self.nodes.indices() {
trace!("processing {:?}, changed_nodes: {:?}", id, changed_nodes);
// Check if any predecessor has changed, and if not then short-circuit.
//
// We handle the start node specially, since it doesn't have any predecessors,
// but we need to start somewhere.
if match id.index() {
0 => !changed_nodes.contains(id),
_ => !preds[id].iter().any(|pred| changed_nodes.contains(*pred)),
} {
trace!("short-circuiting because none of {:?} have changed", preds[id]);
unchanged_mask.remove(id);
continue;
}
if id.index() == 0 {
new_state.clear();
} else {
// If we are not the start node and we have no predecessors, treat
// everything as dropped because there's no way to get here anyway.
new_state.insert_all();
};
for pred in &preds[id] {
new_state.intersect(&self.nodes[*pred].drop_state);
}
for drop in &self.nodes[id].drops {
new_state.insert(*drop);
}
for reinit in &self.nodes[id].reinits {
new_state.remove(*reinit);
}
if self.nodes[id].drop_state.intersect(&new_state) {
changed_nodes.insert(id);
changed = true;
} else {
unchanged_mask.remove(id);
}
}
changed_nodes.intersect(&unchanged_mask);
changed
};
while propagate() {
trace!("drop_state changed, re-running propagation");
}
trace!("after fixpoint: {:#?}", self);
}
fn compute_predecessors(&self) -> IndexVec<PostOrderId, Vec<PostOrderId>> {
let mut preds = IndexVec::from_fn_n(|_| vec![], self.nodes.len());
for (id, node) in self.nodes.iter_enumerated() {
// If the node has no explicit successors, we assume that control
// will from this node into the next one.
//
// If there are successors listed, then we assume that all
// possible successors are given and we do not include the default.
if node.successors.len() == 0 && id.index() != self.nodes.len() - 1 {
preds[id + 1].push(id);
} else {
for succ in &node.successors {
preds[*succ].push(id);
}
}
}
preds
}
}

96
compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs
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@ -1,96 +0,0 @@
//! Implementation of GraphWalk for DropRanges so we can visualize the control
//! flow graph when needed for debugging.
use rustc_graphviz as dot;
use rustc_hir::{Expr, ExprKind, Node};
use rustc_middle::ty::TyCtxt;
use super::{DropRangesBuilder, PostOrderId};
/// Writes the CFG for DropRangesBuilder to a .dot file for visualization.
///
/// It is not normally called, but is kept around to easily add debugging
/// code when needed.
pub(super) fn write_graph_to_file(
drop_ranges: &DropRangesBuilder,
filename: &str,
tcx: TyCtxt<'_>,
) {
dot::render(
&DropRangesGraph { drop_ranges, tcx },
&mut std::fs::File::create(filename).unwrap(),
)
.unwrap();
}
struct DropRangesGraph<'a, 'tcx> {
drop_ranges: &'a DropRangesBuilder,
tcx: TyCtxt<'tcx>,
}
impl<'a> dot::GraphWalk<'a> for DropRangesGraph<'_, '_> {
type Node = PostOrderId;
type Edge = (PostOrderId, PostOrderId);
fn nodes(&'a self) -> dot::Nodes<'a, Self::Node> {
self.drop_ranges.nodes.iter_enumerated().map(|(i, _)| i).collect()
}
fn edges(&'a self) -> dot::Edges<'a, Self::Edge> {
self.drop_ranges
.nodes
.iter_enumerated()
.flat_map(|(i, node)| {
if node.successors.len() == 0 {
vec![(i, i + 1)]
} else {
node.successors.iter().map(move |&s| (i, s)).collect()
}
})
.collect()
}
fn source(&'a self, edge: &Self::Edge) -> Self::Node {
edge.0
}
fn target(&'a self, edge: &Self::Edge) -> Self::Node {
edge.1
}
}
impl<'a> dot::Labeller<'a> for DropRangesGraph<'_, '_> {
type Node = PostOrderId;
type Edge = (PostOrderId, PostOrderId);
fn graph_id(&'a self) -> dot::Id<'a> {
dot::Id::new("drop_ranges").unwrap()
}
fn node_id(&'a self, n: &Self::Node) -> dot::Id<'a> {
dot::Id::new(format!("id{}", n.index())).unwrap()
}
fn node_label(&'a self, n: &Self::Node) -> dot::LabelText<'a> {
dot::LabelText::LabelStr(
format!(
"{n:?}: {}",
self.drop_ranges
.post_order_map
.iter()
.find(|(_hir_id, &post_order_id)| post_order_id == *n)
.map_or("<unknown>".into(), |(hir_id, _)| format!(
"{}{}",
self.tcx.hir().node_to_string(*hir_id),
match self.tcx.hir().find(*hir_id) {
Some(Node::Expr(Expr { kind: ExprKind::Yield(..), .. })) => " (yield)",
_ => "",
}
))
)
.into(),
)
}
}

306
compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/mod.rs
View file

@ -1,306 +0,0 @@
//! Drop range analysis finds the portions of the tree where a value is guaranteed to be dropped
//! (i.e. moved, uninitialized, etc.). This is used to exclude the types of those values from the
//! generator type. See `InteriorVisitor::record` for where the results of this analysis are used.
//!
//! There are three phases to this analysis:
//! 1. Use `ExprUseVisitor` to identify the interesting values that are consumed and borrowed.
//! 2. Use `DropRangeVisitor` to find where the interesting values are dropped or reinitialized,
//! and also build a control flow graph.
//! 3. Use `DropRanges::propagate_to_fixpoint` to flow the dropped/reinitialized information through
//! the CFG and find the exact points where we know a value is definitely dropped.
//!
//! The end result is a data structure that maps the post-order index of each node in the HIR tree
//! to a set of values that are known to be dropped at that location.
use self::cfg_build::build_control_flow_graph;
use self::record_consumed_borrow::find_consumed_and_borrowed;
use crate::FnCtxt;
use hir::def_id::DefId;
use hir::{Body, HirId, HirIdMap, Node};
use rustc_data_structures::unord::{UnordMap, UnordSet};
use rustc_hir as hir;
use rustc_index::bit_set::BitSet;
use rustc_index::IndexVec;
use rustc_middle::hir::map::Map;
use rustc_middle::hir::place::{PlaceBase, PlaceWithHirId};
use rustc_middle::ty;
use std::collections::BTreeMap;
use std::fmt::Debug;
mod cfg_build;
mod cfg_propagate;
mod cfg_visualize;
mod record_consumed_borrow;
pub fn compute_drop_ranges<'a, 'tcx>(
fcx: &'a FnCtxt<'a, 'tcx>,
def_id: DefId,
body: &'tcx Body<'tcx>,
) -> DropRanges {
if fcx.sess().opts.unstable_opts.drop_tracking {
let consumed_borrowed_places = find_consumed_and_borrowed(fcx, def_id, body);
let typeck_results = &fcx.typeck_results.borrow();
let num_exprs = fcx.tcx.region_scope_tree(def_id).body_expr_count(body.id()).unwrap_or(0);
let (mut drop_ranges, borrowed_temporaries) = build_control_flow_graph(
&fcx,
typeck_results,
fcx.param_env,
consumed_borrowed_places,
body,
num_exprs,
);
drop_ranges.propagate_to_fixpoint();
debug!("borrowed_temporaries = {borrowed_temporaries:?}");
DropRanges {
tracked_value_map: drop_ranges.tracked_value_map,
nodes: drop_ranges.nodes,
borrowed_temporaries: Some(borrowed_temporaries),
}
} else {
// If drop range tracking is not enabled, skip all the analysis and produce an
// empty set of DropRanges.
DropRanges {
tracked_value_map: UnordMap::default(),
nodes: IndexVec::new(),
borrowed_temporaries: None,
}
}
}
/// Applies `f` to consumable node in the HIR subtree pointed to by `place`.
///
/// This includes the place itself, and if the place is a reference to a local
/// variable then `f` is also called on the HIR node for that variable as well.
///
/// For example, if `place` points to `foo()`, then `f` is called once for the
/// result of `foo`. On the other hand, if `place` points to `x` then `f` will
/// be called both on the `ExprKind::Path` node that represents the expression
/// as well as the HirId of the local `x` itself.
fn for_each_consumable(hir: Map<'_>, place: TrackedValue, mut f: impl FnMut(TrackedValue)) {
f(place);
let node = hir.find(place.hir_id());
if let Some(Node::Expr(expr)) = node {
match expr.kind {
hir::ExprKind::Path(hir::QPath::Resolved(
_,
hir::Path { res: hir::def::Res::Local(hir_id), .. },
)) => {
f(TrackedValue::Variable(*hir_id));
}
_ => (),
}
}
}
rustc_index::newtype_index! {
#[debug_format = "id({})"]
pub struct PostOrderId {}
}
rustc_index::newtype_index! {
#[debug_format = "hidx({})"]
pub struct TrackedValueIndex {}
}
/// Identifies a value whose drop state we need to track.
#[derive(PartialEq, Eq, Hash, Clone, Copy)]
enum TrackedValue {
/// Represents a named variable, such as a let binding, parameter, or upvar.
///
/// The HirId points to the variable's definition site.
Variable(HirId),
/// A value produced as a result of an expression.
///
/// The HirId points to the expression that returns this value.
Temporary(HirId),
}
impl Debug for TrackedValue {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
ty::tls::with_opt(|opt_tcx| {
if let Some(tcx) = opt_tcx {
write!(f, "{}", tcx.hir().node_to_string(self.hir_id()))
} else {
match self {
Self::Variable(hir_id) => write!(f, "Variable({hir_id:?})"),
Self::Temporary(hir_id) => write!(f, "Temporary({hir_id:?})"),
}
}
})
}
}
impl TrackedValue {
fn hir_id(&self) -> HirId {
match self {
TrackedValue::Variable(hir_id) | TrackedValue::Temporary(hir_id) => *hir_id,
}
}
fn from_place_with_projections_allowed(place_with_id: &PlaceWithHirId<'_>) -> Self {
match place_with_id.place.base {
PlaceBase::Rvalue | PlaceBase::StaticItem => {
TrackedValue::Temporary(place_with_id.hir_id)
}
PlaceBase::Local(hir_id)
| PlaceBase::Upvar(ty::UpvarId { var_path: ty::UpvarPath { hir_id }, .. }) => {
TrackedValue::Variable(hir_id)
}
}
}
}
/// Represents a reason why we might not be able to convert a HirId or Place
/// into a tracked value.
#[derive(Debug)]
enum TrackedValueConversionError {
/// Place projects are not currently supported.
///
/// The reasoning around these is kind of subtle, so we choose to be more
/// conservative around these for now. There is no reason in theory we
/// cannot support these, we just have not implemented it yet.
PlaceProjectionsNotSupported,
}
impl TryFrom<&PlaceWithHirId<'_>> for TrackedValue {
type Error = TrackedValueConversionError;
fn try_from(place_with_id: &PlaceWithHirId<'_>) -> Result<Self, Self::Error> {
if !place_with_id.place.projections.is_empty() {
debug!(
"TrackedValue from PlaceWithHirId: {:?} has projections, which are not supported.",
place_with_id
);
return Err(TrackedValueConversionError::PlaceProjectionsNotSupported);
}
Ok(TrackedValue::from_place_with_projections_allowed(place_with_id))
}
}
pub struct DropRanges {
tracked_value_map: UnordMap<TrackedValue, TrackedValueIndex>,
nodes: IndexVec<PostOrderId, NodeInfo>,
borrowed_temporaries: Option<UnordSet<HirId>>,
}
impl DropRanges {
pub fn is_dropped_at(&self, hir_id: HirId, location: usize) -> bool {
self.tracked_value_map
.get(&TrackedValue::Temporary(hir_id))
.or(self.tracked_value_map.get(&TrackedValue::Variable(hir_id)))
.cloned()
.is_some_and(|tracked_value_id| {
self.expect_node(location.into()).drop_state.contains(tracked_value_id)
})
}
pub fn is_borrowed_temporary(&self, expr: &hir::Expr<'_>) -> bool {
if let Some(b) = &self.borrowed_temporaries { b.contains(&expr.hir_id) } else { true }
}
/// Returns a reference to the NodeInfo for a node, panicking if it does not exist
fn expect_node(&self, id: PostOrderId) -> &NodeInfo {
&self.nodes[id]
}
}
/// Tracks information needed to compute drop ranges.
struct DropRangesBuilder {
/// The core of DropRangesBuilder is a set of nodes, which each represent
/// one expression. We primarily refer to them by their index in a
/// post-order traversal of the HIR tree, since this is what
/// generator_interior uses to talk about yield positions.
///
/// This IndexVec keeps the relevant details for each node. See the
/// NodeInfo struct for more details, but this information includes things
/// such as the set of control-flow successors, which variables are dropped
/// or reinitialized, and whether each variable has been inferred to be
/// known-dropped or potentially reinitialized at each point.
nodes: IndexVec<PostOrderId, NodeInfo>,
/// We refer to values whose drop state we are tracking by the HirId of
/// where they are defined. Within a NodeInfo, however, we store the
/// drop-state in a bit vector indexed by a HirIdIndex
/// (see NodeInfo::drop_state). The hir_id_map field stores the mapping
/// from HirIds to the HirIdIndex that is used to represent that value in
/// bitvector.
tracked_value_map: UnordMap<TrackedValue, TrackedValueIndex>,
/// When building the control flow graph, we don't always know the
/// post-order index of the target node at the point we encounter it.
/// For example, this happens with break and continue. In those cases,
/// we store a pair of the PostOrderId of the source and the HirId
/// of the target. Once we have gathered all of these edges, we make a
/// pass over the set of deferred edges (see process_deferred_edges in
/// cfg_build.rs), look up the PostOrderId for the target (since now the
/// post-order index for all nodes is known), and add missing control flow
/// edges.
deferred_edges: Vec<(PostOrderId, HirId)>,
/// This maps HirIds of expressions to their post-order index. It is
/// used in process_deferred_edges to correctly add back-edges.
post_order_map: HirIdMap<PostOrderId>,
}
impl Debug for DropRangesBuilder {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("DropRanges")
.field("hir_id_map", &self.tracked_value_map)
.field("post_order_maps", &self.post_order_map)
.field("nodes", &self.nodes.iter_enumerated().collect::<BTreeMap<_, _>>())
.finish()
}
}
/// DropRanges keeps track of what values are definitely dropped at each point in the code.
///
/// Values of interest are defined by the hir_id of their place. Locations in code are identified
/// by their index in the post-order traversal. At its core, DropRanges maps
/// (hir_id, post_order_id) -> bool, where a true value indicates that the value is definitely
/// dropped at the point of the node identified by post_order_id.
impl DropRangesBuilder {
/// Returns the number of values (hir_ids) that are tracked
fn num_values(&self) -> usize {
self.tracked_value_map.len()
}
fn node_mut(&mut self, id: PostOrderId) -> &mut NodeInfo {
let size = self.num_values();
self.nodes.ensure_contains_elem(id, || NodeInfo::new(size))
}
fn add_control_edge(&mut self, from: PostOrderId, to: PostOrderId) {
trace!("adding control edge from {:?} to {:?}", from, to);
self.node_mut(from).successors.push(to);
}
}
#[derive(Debug)]
struct NodeInfo {
/// IDs of nodes that can follow this one in the control flow
///
/// If the vec is empty, then control proceeds to the next node.
successors: Vec<PostOrderId>,
/// List of hir_ids that are dropped by this node.
drops: Vec<TrackedValueIndex>,
/// List of hir_ids that are reinitialized by this node.
reinits: Vec<TrackedValueIndex>,
/// Set of values that are definitely dropped at this point.
drop_state: BitSet<TrackedValueIndex>,
}
impl NodeInfo {
fn new(num_values: usize) -> Self {
Self {
successors: vec![],
drops: vec![],
reinits: vec![],
drop_state: BitSet::new_filled(num_values),
}
}
}

242
compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs
View file

@ -1,242 +0,0 @@
use super::TrackedValue;
use crate::{
expr_use_visitor::{self, ExprUseVisitor},
FnCtxt,
};
use hir::{def_id::DefId, Body, HirId, HirIdMap};
use rustc_data_structures::{fx::FxIndexSet, unord::UnordSet};
use rustc_hir as hir;
use rustc_middle::ty::{ParamEnv, TyCtxt};
use rustc_middle::{
hir::place::{PlaceBase, Projection, ProjectionKind},
ty::TypeVisitableExt,
};
pub(super) fn find_consumed_and_borrowed<'a, 'tcx>(
fcx: &'a FnCtxt<'a, 'tcx>,
def_id: DefId,
body: &'tcx Body<'tcx>,
) -> ConsumedAndBorrowedPlaces {
let mut expr_use_visitor = ExprUseDelegate::new(fcx.tcx, fcx.param_env);
expr_use_visitor.consume_body(fcx, def_id, body);
expr_use_visitor.places
}
pub(super) struct ConsumedAndBorrowedPlaces {
/// Records the variables/expressions that are dropped by a given expression.
///
/// The key is the hir-id of the expression, and the value is a set or hir-ids for variables
/// or values that are consumed by that expression.
///
/// Note that this set excludes "partial drops" -- for example, a statement like `drop(x.y)` is
/// not considered a drop of `x`, although it would be a drop of `x.y`.
pub(super) consumed: HirIdMap<FxIndexSet<TrackedValue>>,
/// A set of hir-ids of values or variables that are borrowed at some point within the body.
pub(super) borrowed: UnordSet<TrackedValue>,
/// A set of hir-ids of values or variables that are borrowed at some point within the body.
pub(super) borrowed_temporaries: UnordSet<HirId>,
}
/// Works with ExprUseVisitor to find interesting values for the drop range analysis.
///
/// Interesting values are those that are either dropped or borrowed. For dropped values, we also
/// record the parent expression, which is the point where the drop actually takes place.
struct ExprUseDelegate<'tcx> {
tcx: TyCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
places: ConsumedAndBorrowedPlaces,
}
impl<'tcx> ExprUseDelegate<'tcx> {
fn new(tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Self {
Self {
tcx,
param_env,
places: ConsumedAndBorrowedPlaces {
consumed: <_>::default(),
borrowed: <_>::default(),
borrowed_temporaries: <_>::default(),
},
}
}
fn consume_body(&mut self, fcx: &'_ FnCtxt<'_, 'tcx>, def_id: DefId, body: &'tcx Body<'tcx>) {
// Run ExprUseVisitor to find where values are consumed.
ExprUseVisitor::new(
self,
&fcx.infcx,
def_id.expect_local(),
fcx.param_env,
&fcx.typeck_results.borrow(),
)
.consume_body(body);
}
fn mark_consumed(&mut self, consumer: HirId, target: TrackedValue) {
self.places.consumed.entry(consumer).or_insert_with(|| <_>::default());
debug!(?consumer, ?target, "mark_consumed");
self.places.consumed.get_mut(&consumer).map(|places| places.insert(target));
}
fn borrow_place(&mut self, place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>) {
self.places
.borrowed
.insert(TrackedValue::from_place_with_projections_allowed(place_with_id));
// Ordinarily a value is consumed by it's parent, but in the special case of a
// borrowed RValue, we create a reference that lives as long as the temporary scope
// for that expression (typically, the innermost statement, but sometimes the enclosing
// block). We record this fact here so that later in generator_interior
// we can use the correct scope.
//
// We special case borrows through a dereference (`&*x`, `&mut *x` where `x` is
// some rvalue expression), since these are essentially a copy of a pointer.
// In other words, this borrow does not refer to the
// temporary (`*x`), but to the referent (whatever `x` is a borrow of).
//
// We were considering that we might encounter problems down the line if somehow,
// some part of the compiler were to look at this result and try to use it to
// drive a borrowck-like analysis (this does not currently happen, as of this writing).
// But even this should be fine, because the lifetime of the dereferenced reference
// found in the rvalue is only significant as an intermediate 'link' to the value we
// are producing, and we separately track whether that value is live over a yield.
// Example:
//
// ```notrust
// fn identity<T>(x: &mut T) -> &mut T { x }
// let a: A = ...;
// let y: &'y mut A = &mut *identity(&'a mut a);
// ^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow we are talking about
// ```
//
// The expression `*identity(...)` is a deref of an rvalue,
// where the `identity(...)` (the rvalue) produces a return type
// of `&'rv mut A`, where `'a: 'rv`. We then assign this result to
// `'y`, resulting in (transitively) `'a: 'y` (i.e., while `y` is in use,
// `a` will be considered borrowed). Other parts of the code will ensure
// that if `y` is live over a yield, `&'y mut A` appears in the generator
// state. If `'y` is live, then any sound region analysis must conclude
// that `'a` is also live. So if this causes a bug, blame some other
// part of the code!
let is_deref = place_with_id
.place
.projections
.iter()
.any(|Projection { kind, .. }| *kind == ProjectionKind::Deref);
if let (false, PlaceBase::Rvalue) = (is_deref, place_with_id.place.base) {
self.places.borrowed_temporaries.insert(place_with_id.hir_id);
}
}
}
impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
fn consume(
&mut self,
place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
diag_expr_id: HirId,
) {
let hir = self.tcx.hir();
let parent = match hir.opt_parent_id(place_with_id.hir_id) {
Some(parent) => parent,
None => place_with_id.hir_id,
};
debug!(
"consume {:?}; diag_expr_id={}, using parent {}",
place_with_id,
hir.node_to_string(diag_expr_id),
hir.node_to_string(parent)
);
if let Ok(tracked_value) = place_with_id.try_into() {
self.mark_consumed(parent, tracked_value)
}
}
fn borrow(
&mut self,
place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
diag_expr_id: HirId,
bk: rustc_middle::ty::BorrowKind,
) {
debug!(
"borrow: place_with_id = {place_with_id:#?}, diag_expr_id={diag_expr_id:#?}, \
borrow_kind={bk:#?}"
);
self.borrow_place(place_with_id);
}
fn copy(
&mut self,
place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
_diag_expr_id: HirId,
) {
debug!("copy: place_with_id = {place_with_id:?}");
self.places
.borrowed
.insert(TrackedValue::from_place_with_projections_allowed(place_with_id));
// For copied we treat this mostly like a borrow except that we don't add the place
// to borrowed_temporaries because the copy is consumed.
}
fn mutate(
&mut self,
assignee_place: &expr_use_visitor::PlaceWithHirId<'tcx>,
diag_expr_id: HirId,
) {
debug!("mutate {assignee_place:?}; diag_expr_id={diag_expr_id:?}");
if assignee_place.place.base == PlaceBase::Rvalue
&& assignee_place.place.projections.is_empty()
{
// Assigning to an Rvalue is illegal unless done through a dereference. We would have
// already gotten a type error, so we will just return here.
return;
}
// If the type being assigned needs dropped, then the mutation counts as a borrow
// since it is essentially doing `Drop::drop(&mut x); x = new_value;`.
let ty = self.tcx.erase_regions(assignee_place.place.base_ty);
if ty.has_infer() {
self.tcx.sess.delay_span_bug(
self.tcx.hir().span(assignee_place.hir_id),
format!("inference variables in {ty}"),
);
} else if ty.needs_drop(self.tcx, self.param_env) {
self.places
.borrowed
.insert(TrackedValue::from_place_with_projections_allowed(assignee_place));
}
}
fn bind(
&mut self,
binding_place: &expr_use_visitor::PlaceWithHirId<'tcx>,
diag_expr_id: HirId,
) {
debug!("bind {binding_place:?}; diag_expr_id={diag_expr_id:?}");
}
fn fake_read(
&mut self,
place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
cause: rustc_middle::mir::FakeReadCause,
diag_expr_id: HirId,
) {
debug!(
"fake_read place_with_id={place_with_id:?}; cause={cause:?}; diag_expr_id={diag_expr_id:?}"
);
// fake reads happen in places like the scrutinee of a match expression.
// we treat those as a borrow, much like a copy: the idea is that we are
// transiently creating a `&T` ref that we can read from to observe the current
// value (this `&T` is immediately dropped afterwards).
self.borrow_place(place_with_id);
}
}

723
compiler/rustc_hir_typeck/src/generator_interior/mod.rs
View file

@ -1,723 +0,0 @@
//! This calculates the types which has storage which lives across a suspension point in a
//! generator from the perspective of typeck. The actual types used at runtime
//! is calculated in `rustc_mir_transform::generator` and may be a subset of the
//! types computed here.
use self::drop_ranges::DropRanges;
use super::FnCtxt;
use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
use rustc_errors::{pluralize, DelayDm};
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::hir_id::HirIdSet;
use rustc_hir::intravisit::{self, Visitor};
use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind};
use rustc_infer::infer::{DefineOpaqueTypes, RegionVariableOrigin};
use rustc_middle::middle::region::{self, Scope, ScopeData, YieldData};
use rustc_middle::traits::ObligationCauseCode;
use rustc_middle::ty::fold::FnMutDelegate;
use rustc_middle::ty::{self, BoundVariableKind, RvalueScopes, Ty, TyCtxt, TypeVisitableExt};
use rustc_span::symbol::sym;
use rustc_span::Span;
use smallvec::{smallvec, SmallVec};
mod drop_ranges;
struct InteriorVisitor<'a, 'tcx> {
fcx: &'a FnCtxt<'a, 'tcx>,
region_scope_tree: &'a region::ScopeTree,
types: FxIndexSet<ty::GeneratorInteriorTypeCause<'tcx>>,
rvalue_scopes: &'a RvalueScopes,
expr_count: usize,
kind: hir::GeneratorKind,
prev_unresolved_span: Option<Span>,
linted_values: HirIdSet,
drop_ranges: DropRanges,
}
impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
fn record(
&mut self,
ty: Ty<'tcx>,
hir_id: HirId,
scope: Option<region::Scope>,
expr: Option<&'tcx Expr<'tcx>>,
source_span: Span,
) {
use rustc_span::DUMMY_SP;
let ty = self.fcx.resolve_vars_if_possible(ty);
debug!(
"attempting to record type ty={:?}; hir_id={:?}; scope={:?}; expr={:?}; source_span={:?}; expr_count={:?}",
ty, hir_id, scope, expr, source_span, self.expr_count,
);
let live_across_yield = scope
.map(|s| {
self.region_scope_tree.yield_in_scope(s).and_then(|yield_data| {
// If we are recording an expression that is the last yield
// in the scope, or that has a postorder CFG index larger
// than the one of all of the yields, then its value can't
// be storage-live (and therefore live) at any of the yields.
//
// See the mega-comment at `yield_in_scope` for a proof.
yield_data
.iter()
.find(|yield_data| {
debug!(
"comparing counts yield: {} self: {}, source_span = {:?}",
yield_data.expr_and_pat_count, self.expr_count, source_span
);
if self
.is_dropped_at_yield_location(hir_id, yield_data.expr_and_pat_count)
{
debug!("value is dropped at yield point; not recording");
return false;
}
// If it is a borrowing happening in the guard,
// it needs to be recorded regardless because they
// do live across this yield point.
yield_data.expr_and_pat_count >= self.expr_count
})
.cloned()
})
})
.unwrap_or_else(|| {
Some(YieldData { span: DUMMY_SP, expr_and_pat_count: 0, source: self.kind.into() })
});
if let Some(yield_data) = live_across_yield {
debug!(
"type in expr = {:?}, scope = {:?}, type = {:?}, count = {}, yield_span = {:?}",
expr, scope, ty, self.expr_count, yield_data.span
);
if let Some((unresolved_term, unresolved_type_span)) =
self.fcx.first_unresolved_const_or_ty_var(&ty)
{
// If unresolved type isn't a ty_var then unresolved_type_span is None
let span = self
.prev_unresolved_span
.unwrap_or_else(|| unresolved_type_span.unwrap_or(source_span));
// If we encounter an int/float variable, then inference fallback didn't
// finish due to some other error. Don't emit spurious additional errors.
if let Some(unresolved_ty) = unresolved_term.ty()
&& let ty::Infer(ty::InferTy::IntVar(_) | ty::InferTy::FloatVar(_)) = unresolved_ty.kind()
{
self.fcx
.tcx
.sess
.delay_span_bug(span, format!("Encountered var {unresolved_term:?}"));
} else {
let note = format!(
"the type is part of the {} because of this {}",
self.kind.descr(),
yield_data.source
);
self.fcx
.need_type_info_err_in_generator(self.kind, span, unresolved_term)
.span_note(yield_data.span, note)
.emit();
}
} else {
// Insert the type into the ordered set.
let scope_span = scope.map(|s| s.span(self.fcx.tcx, self.region_scope_tree));
if !self.linted_values.contains(&hir_id) {
check_must_not_suspend_ty(
self.fcx,
ty,
hir_id,
SuspendCheckData {
expr,
source_span,
yield_span: yield_data.span,
plural_len: 1,
..Default::default()
},
);
self.linted_values.insert(hir_id);
}
self.types.insert(ty::GeneratorInteriorTypeCause {
span: source_span,
ty,
scope_span,
yield_span: yield_data.span,
expr: expr.map(|e| e.hir_id),
});
}
} else {
debug!(
"no type in expr = {:?}, count = {:?}, span = {:?}",
expr,
self.expr_count,
expr.map(|e| e.span)
);
if let Some((unresolved_type, unresolved_type_span)) =
self.fcx.first_unresolved_const_or_ty_var(&ty)
{
debug!(
"remained unresolved_type = {:?}, unresolved_type_span: {:?}",
unresolved_type, unresolved_type_span
);
self.prev_unresolved_span = unresolved_type_span;
}
}
}
/// If drop tracking is enabled, consult drop_ranges to see if a value is
/// known to be dropped at a yield point and therefore can be omitted from
/// the generator witness.
fn is_dropped_at_yield_location(&self, value_hir_id: HirId, yield_location: usize) -> bool {
// short-circuit if drop tracking is not enabled.
if !self.fcx.sess().opts.unstable_opts.drop_tracking {
return false;
}
self.drop_ranges.is_dropped_at(value_hir_id, yield_location)
}
}
pub fn resolve_interior<'a, 'tcx>(
fcx: &'a FnCtxt<'a, 'tcx>,
def_id: DefId,
generator_def_id: LocalDefId,
body_id: hir::BodyId,
interior: Ty<'tcx>,
kind: hir::GeneratorKind,
) {
let body = fcx.tcx.hir().body(body_id);
let typeck_results = fcx.inh.typeck_results.borrow();
let mut visitor = InteriorVisitor {
fcx,
types: FxIndexSet::default(),
region_scope_tree: fcx.tcx.region_scope_tree(def_id),
rvalue_scopes: &typeck_results.rvalue_scopes,
expr_count: 0,
kind,
prev_unresolved_span: None,
linted_values: <_>::default(),
drop_ranges: drop_ranges::compute_drop_ranges(fcx, def_id, body),
};
intravisit::walk_body(&mut visitor, body);
// Check that we visited the same amount of expressions as the RegionResolutionVisitor
let region_expr_count = fcx.tcx.region_scope_tree(def_id).body_expr_count(body_id).unwrap();
assert_eq!(region_expr_count, visitor.expr_count);
// The types are already kept in insertion order.
let types = visitor.types;
if fcx.tcx.features().unsized_locals || fcx.tcx.features().unsized_fn_params {
for interior_ty in &types {
fcx.require_type_is_sized(
interior_ty.ty,
interior_ty.span,
ObligationCauseCode::SizedGeneratorInterior(generator_def_id),
);
}
}
// The types in the generator interior contain lifetimes local to the generator itself,
// which should not be exposed outside of the generator. Therefore, we replace these
// lifetimes with existentially-bound lifetimes, which reflect the exact value of the
// lifetimes not being known by users.
//
// These lifetimes are used in auto trait impl checking (for example,
// if a Sync generator contains an &'α T, we need to check whether &'α T: Sync),
// so knowledge of the exact relationships between them isn't particularly important.
debug!("types in generator {:?}, span = {:?}", types, body.value.span);
// We want to deduplicate if the lifetimes are the same modulo some non-informative counter.
// So, we need to actually do two passes: first by type to anonymize (preserving information
// required for diagnostics), then a second pass over all captured types to reassign disjoint
// region indices.
let mut captured_tys = FxHashSet::default();
let type_causes: Vec<_> = types
.into_iter()
.filter_map(|mut cause| {
// Replace all regions inside the generator interior with late bound regions.
// Note that each region slot in the types gets a new fresh late bound region,
// which means that none of the regions inside relate to any other, even if
// typeck had previously found constraints that would cause them to be related.
let mut counter = 0;
let mut mk_bound_region = |kind| {
let var = ty::BoundVar::from_u32(counter);
counter += 1;
ty::BoundRegion { var, kind }
};
let ty = fcx.normalize(cause.span, cause.ty);
let ty = fcx.tcx.fold_regions(ty, |region, current_depth| {
let br = match region.kind() {
ty::ReVar(vid) => {
let origin = fcx.region_var_origin(vid);
match origin {
RegionVariableOrigin::EarlyBoundRegion(span, _) => {
mk_bound_region(ty::BrAnon(Some(span)))
}
_ => mk_bound_region(ty::BrAnon(None)),
}
}
ty::ReEarlyBound(region) => {
mk_bound_region(ty::BrNamed(region.def_id, region.name))
}
ty::ReLateBound(_, ty::BoundRegion { kind, .. })
| ty::ReFree(ty::FreeRegion { bound_region: kind, .. }) => match kind {
ty::BoundRegionKind::BrAnon(span) => mk_bound_region(ty::BrAnon(span)),
ty::BoundRegionKind::BrNamed(def_id, sym) => {
mk_bound_region(ty::BrNamed(def_id, sym))
}
ty::BoundRegionKind::BrEnv => mk_bound_region(ty::BrAnon(None)),
},
_ => mk_bound_region(ty::BrAnon(None)),
};
let r = ty::Region::new_late_bound(fcx.tcx, current_depth, br);
r
});
captured_tys.insert(ty).then(|| {
cause.ty = ty;
cause
})
})
.collect();
let mut bound_vars: SmallVec<[BoundVariableKind; 4]> = smallvec![];
let mut counter = 0;
// Optimization: If there is only one captured type, then we don't actually
// need to fold and reindex (since the first type doesn't change).
let type_causes = if captured_tys.len() > 0 {
// Optimization: Use `replace_escaping_bound_vars_uncached` instead of
// `fold_regions`, since we only have late bound regions, and it skips
// types without bound regions.
fcx.tcx.replace_escaping_bound_vars_uncached(
type_causes,
FnMutDelegate {
regions: &mut |br| {
let kind = br.kind;
let var = ty::BoundVar::from_usize(bound_vars.len());
bound_vars.push(ty::BoundVariableKind::Region(kind));
counter += 1;
ty::Region::new_late_bound(
fcx.tcx,
ty::INNERMOST,
ty::BoundRegion { var, kind },
)
},
types: &mut |b| bug!("unexpected bound ty in binder: {b:?}"),
consts: &mut |b, ty| bug!("unexpected bound ct in binder: {b:?} {ty}"),
},
)
} else {
type_causes
};
// Extract type components to build the witness type.
let type_list = fcx.tcx.mk_type_list_from_iter(type_causes.iter().map(|cause| cause.ty));
let bound_vars = fcx.tcx.mk_bound_variable_kinds(&bound_vars);
let witness =
Ty::new_generator_witness(fcx.tcx, ty::Binder::bind_with_vars(type_list, bound_vars));
drop(typeck_results);
// Store the generator types and spans into the typeck results for this generator.
fcx.inh.typeck_results.borrow_mut().generator_interior_types =
ty::Binder::bind_with_vars(type_causes, bound_vars);
debug!(
"types in generator after region replacement {:?}, span = {:?}",
witness, body.value.span
);
// Unify the type variable inside the generator with the new witness
match fcx.at(&fcx.misc(body.value.span), fcx.param_env).eq(
DefineOpaqueTypes::No,
interior,
witness,
) {
Ok(ok) => fcx.register_infer_ok_obligations(ok),
_ => bug!("failed to relate {interior} and {witness}"),
}
}
// This visitor has to have the same visit_expr calls as RegionResolutionVisitor in
// librustc_middle/middle/region.rs since `expr_count` is compared against the results
// there.
impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
fn visit_arm(&mut self, arm: &'tcx Arm<'tcx>) {
let Arm { guard, pat, body, .. } = arm;
self.visit_pat(pat);
if let Some(ref g) = guard {
{
// If there is a guard, we need to count all variables bound in the pattern as
// borrowed for the entire guard body, regardless of whether they are accessed.
// We do this by walking the pattern bindings and recording `&T` for any `x: T`
// that is bound.
struct ArmPatCollector<'a, 'b, 'tcx> {
interior_visitor: &'a mut InteriorVisitor<'b, 'tcx>,
scope: Scope,
}
impl<'a, 'b, 'tcx> Visitor<'tcx> for ArmPatCollector<'a, 'b, 'tcx> {
fn visit_pat(&mut self, pat: &'tcx Pat<'tcx>) {
intravisit::walk_pat(self, pat);
if let PatKind::Binding(_, id, ident, ..) = pat.kind {
let ty =
self.interior_visitor.fcx.typeck_results.borrow().node_type(id);
let tcx = self.interior_visitor.fcx.tcx;
let ty = Ty::new_ref(
tcx,
// Use `ReErased` as `resolve_interior` is going to replace all the
// regions anyway.
tcx.lifetimes.re_erased,
ty::TypeAndMut { ty, mutbl: hir::Mutability::Not },
);
self.interior_visitor.record(
ty,
id,
Some(self.scope),
None,
ident.span,
);
}
}
}
ArmPatCollector {
interior_visitor: self,
scope: Scope { id: g.body().hir_id.local_id, data: ScopeData::Node },
}
.visit_pat(pat);
}
match g {
Guard::If(ref e) => {
self.visit_expr(e);
}
Guard::IfLet(ref l) => {
self.visit_let_expr(l);
}
}
}
self.visit_expr(body);
}
fn visit_pat(&mut self, pat: &'tcx Pat<'tcx>) {
intravisit::walk_pat(self, pat);
self.expr_count += 1;
if let PatKind::Binding(..) = pat.kind {
let scope = self.region_scope_tree.var_scope(pat.hir_id.local_id).unwrap();
let ty = self.fcx.typeck_results.borrow().pat_ty(pat);
self.record(ty, pat.hir_id, Some(scope), None, pat.span);
}
}
fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
match &expr.kind {
ExprKind::Call(callee, args) => match &callee.kind {
ExprKind::Path(qpath) => {
let res = self.fcx.typeck_results.borrow().qpath_res(qpath, callee.hir_id);
match res {
// Direct calls never need to keep the callee `ty::FnDef`
// ZST in a temporary, so skip its type, just in case it
// can significantly complicate the generator type.
Res::Def(
DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn),
_,
) => {
// NOTE(eddyb) this assumes a path expression has
// no nested expressions to keep track of.
self.expr_count += 1;
// Record the rest of the call expression normally.
for arg in *args {
self.visit_expr(arg);
}
}
_ => intravisit::walk_expr(self, expr),
}
}
_ => intravisit::walk_expr(self, expr),
},
_ => intravisit::walk_expr(self, expr),
}
self.expr_count += 1;
debug!("is_borrowed_temporary: {:?}", self.drop_ranges.is_borrowed_temporary(expr));
let ty = self.fcx.typeck_results.borrow().expr_ty_adjusted_opt(expr);
// Typically, the value produced by an expression is consumed by its parent in some way,
// so we only have to check if the parent contains a yield (note that the parent may, for
// example, store the value into a local variable, but then we already consider local
// variables to be live across their scope).
//
// However, in the case of temporary values, we are going to store the value into a
// temporary on the stack that is live for the current temporary scope and then return a
// reference to it. That value may be live across the entire temporary scope.
//
// There's another subtlety: if the type has an observable drop, it must be dropped after
// the yield, even if it's not borrowed or referenced after the yield. Ideally this would
// *only* happen for types with observable drop, not all types which wrap them, but that
// doesn't match the behavior of MIR borrowck and causes ICEs. See the FIXME comment in
// tests/ui/generator/drop-tracking-parent-expression.rs.
let scope = if self.drop_ranges.is_borrowed_temporary(expr)
|| ty.map_or(true, |ty| {
// Avoid ICEs in needs_drop.
let ty = self.fcx.resolve_vars_if_possible(ty);
let ty = self.fcx.tcx.erase_regions(ty);
if ty.has_infer() {
self.fcx
.tcx
.sess
.delay_span_bug(expr.span, format!("inference variables in {ty}"));
true
} else {
ty.needs_drop(self.fcx.tcx, self.fcx.param_env)
}
}) {
self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id)
} else {
let parent_expr = self
.fcx
.tcx
.hir()
.parent_iter(expr.hir_id)
.find(|(_, node)| matches!(node, hir::Node::Expr(_)))
.map(|(id, _)| id);
debug!("parent_expr: {:?}", parent_expr);
match parent_expr {
Some(parent) => Some(Scope { id: parent.local_id, data: ScopeData::Node }),
None => {
self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id)
}
}
};
// If there are adjustments, then record the final type --
// this is the actual value that is being produced.
if let Some(adjusted_ty) = ty {
self.record(adjusted_ty, expr.hir_id, scope, Some(expr), expr.span);
}
// Also record the unadjusted type (which is the only type if
// there are no adjustments). The reason for this is that the
// unadjusted value is sometimes a "temporary" that would wind
// up in a MIR temporary.
//
// As an example, consider an expression like `vec![].push(x)`.
// Here, the `vec![]` would wind up MIR stored into a
// temporary variable `t` which we can borrow to invoke
// `<Vec<_>>::push(&mut t, x)`.
//
// Note that an expression can have many adjustments, and we
// are just ignoring those intermediate types. This is because
// those intermediate values are always linearly "consumed" by
// the other adjustments, and hence would never be directly
// captured in the MIR.
//
// (Note that this partly relies on the fact that the `Deref`
// traits always return references, which means their content
// can be reborrowed without needing to spill to a temporary.
// If this were not the case, then we could conceivably have
// to create intermediate temporaries.)
//
// The type table might not have information for this expression
// if it is in a malformed scope. (#66387)
if let Some(ty) = self.fcx.typeck_results.borrow().expr_ty_opt(expr) {
self.record(ty, expr.hir_id, scope, Some(expr), expr.span);
} else {
self.fcx.tcx.sess.delay_span_bug(expr.span, "no type for node");
}
}
}
#[derive(Default)]
struct SuspendCheckData<'a, 'tcx> {
expr: Option<&'tcx Expr<'tcx>>,
source_span: Span,
yield_span: Span,
descr_pre: &'a str,
descr_post: &'a str,
plural_len: usize,
}
// Returns whether it emitted a diagnostic or not
// Note that this fn and the proceeding one are based on the code
// for creating must_use diagnostics
//
// Note that this technique was chosen over things like a `Suspend` marker trait
// as it is simpler and has precedent in the compiler
fn check_must_not_suspend_ty<'tcx>(
fcx: &FnCtxt<'_, 'tcx>,
ty: Ty<'tcx>,
hir_id: HirId,
data: SuspendCheckData<'_, 'tcx>,
) -> bool {
if ty.is_unit()
// FIXME: should this check `Ty::is_inhabited_from`. This query is not available in this stage
// of typeck (before ReVar and RePlaceholder are removed), but may remove noise, like in
// `must_use`
// || !ty.is_inhabited_from(fcx.tcx, fcx.tcx.parent_module(hir_id).to_def_id(), fcx.param_env)
{
return false;
}
let plural_suffix = pluralize!(data.plural_len);
debug!("Checking must_not_suspend for {}", ty);
match *ty.kind() {
ty::Adt(..) if ty.is_box() => {
let boxed_ty = ty.boxed_ty();
let descr_pre = &format!("{}boxed ", data.descr_pre);
check_must_not_suspend_ty(fcx, boxed_ty, hir_id, SuspendCheckData { descr_pre, ..data })
}
ty::Adt(def, _) => check_must_not_suspend_def(fcx.tcx, def.did(), hir_id, data),
// FIXME: support adding the attribute to TAITs
ty::Alias(ty::Opaque, ty::AliasTy { def_id: def, .. }) => {
let mut has_emitted = false;
for &(predicate, _) in fcx.tcx.explicit_item_bounds(def).skip_binder() {
// We only look at the `DefId`, so it is safe to skip the binder here.
if let ty::ClauseKind::Trait(ref poly_trait_predicate) =
predicate.kind().skip_binder()
{
let def_id = poly_trait_predicate.trait_ref.def_id;
let descr_pre = &format!("{}implementer{} of ", data.descr_pre, plural_suffix);
if check_must_not_suspend_def(
fcx.tcx,
def_id,
hir_id,
SuspendCheckData { descr_pre, ..data },
) {
has_emitted = true;
break;
}
}
}
has_emitted
}
ty::Dynamic(binder, _, _) => {
let mut has_emitted = false;
for predicate in binder.iter() {
if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
let def_id = trait_ref.def_id;
let descr_post = &format!(" trait object{}{}", plural_suffix, data.descr_post);
if check_must_not_suspend_def(
fcx.tcx,
def_id,
hir_id,
SuspendCheckData { descr_post, ..data },
) {
has_emitted = true;
break;
}
}
}
has_emitted
}
ty::Tuple(fields) => {
let mut has_emitted = false;
let comps = match data.expr.map(|e| &e.kind) {
Some(hir::ExprKind::Tup(comps)) if comps.len() == fields.len() => Some(comps),
_ => None,
};
for (i, ty) in fields.iter().enumerate() {
let descr_post = &format!(" in tuple element {i}");
let span = comps.and_then(|c| c.get(i)).map(|e| e.span).unwrap_or(data.source_span);
if check_must_not_suspend_ty(
fcx,
ty,
hir_id,
SuspendCheckData {
descr_post,
expr: comps.and_then(|comps| comps.get(i)),
source_span: span,
..data
},
) {
has_emitted = true;
}
}
has_emitted
}
ty::Array(ty, len) => {
let descr_pre = &format!("{}array{} of ", data.descr_pre, plural_suffix);
let target_usize =
len.try_eval_target_usize(fcx.tcx, fcx.param_env).unwrap_or(0) as usize;
let plural_len = target_usize.saturating_add(1);
check_must_not_suspend_ty(
fcx,
ty,
hir_id,
SuspendCheckData { descr_pre, plural_len, ..data },
)
}
// If drop tracking is enabled, we want to look through references, since the referent
// may not be considered live across the await point.
ty::Ref(_region, ty, _mutability) if fcx.sess().opts.unstable_opts.drop_tracking => {
let descr_pre = &format!("{}reference{} to ", data.descr_pre, plural_suffix);
check_must_not_suspend_ty(fcx, ty, hir_id, SuspendCheckData { descr_pre, ..data })
}
_ => false,
}
}
fn check_must_not_suspend_def(
tcx: TyCtxt<'_>,
def_id: DefId,
hir_id: HirId,
data: SuspendCheckData<'_, '_>,
) -> bool {
if let Some(attr) = tcx.get_attr(def_id, sym::must_not_suspend) {
tcx.struct_span_lint_hir(
rustc_session::lint::builtin::MUST_NOT_SUSPEND,
hir_id,
data.source_span,
DelayDm(|| {
format!(
"{}`{}`{} held across a suspend point, but should not be",
data.descr_pre,
tcx.def_path_str(def_id),
data.descr_post,
)
}),
|lint| {
// add span pointing to the offending yield/await
lint.span_label(data.yield_span, "the value is held across this suspend point");
// Add optional reason note
if let Some(note) = attr.value_str() {
// FIXME(guswynn): consider formatting this better
lint.span_note(data.source_span, note.to_string());
}
// Add some quick suggestions on what to do
// FIXME: can `drop` work as a suggestion here as well?
lint.span_help(
data.source_span,
"consider using a block (`{ ... }`) \
to shrink the value's scope, ending before the suspend point",
);
lint
},
);
true
} else {
false
}
}

1
compiler/rustc_hir_typeck/src/lib.rs
View file

@ -32,7 +32,6 @@ pub mod expr_use_visitor;
mod fallback;
mod fn_ctxt;
mod gather_locals;
mod generator_interior;
mod inherited;
mod intrinsicck;
mod mem_categorization;

6
compiler/rustc_hir_typeck/src/writeback.rs
View file

@ -63,7 +63,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
wbcx.visit_coercion_casts();
wbcx.visit_user_provided_tys();
wbcx.visit_user_provided_sigs();
wbcx.visit_generator_interior_types();
wbcx.visit_generator_interior();
wbcx.visit_offset_of_container_types();
wbcx.typeck_results.rvalue_scopes =
@ -538,11 +538,9 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
);
}
fn visit_generator_interior_types(&mut self) {
fn visit_generator_interior(&mut self) {
let fcx_typeck_results = self.fcx.typeck_results.borrow();
assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
self.typeck_results.generator_interior_types =
fcx_typeck_results.generator_interior_types.clone();
self.tcx().with_stable_hashing_context(move |ref hcx| {
for (&expr_def_id, predicates) in
fcx_typeck_results.generator_interior_predicates.to_sorted(hcx, false).into_iter()

2
compiler/rustc_interface/src/passes.rs
View file

@ -798,14 +798,12 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
}
});
if tcx.sess.opts.unstable_opts.drop_tracking_mir {
tcx.hir().par_body_owners(|def_id| {
if let rustc_hir::def::DefKind::Generator = tcx.def_kind(def_id) {
tcx.ensure().mir_generator_witnesses(def_id);
tcx.ensure().check_generator_obligations(def_id);
}
});
}
sess.time("layout_testing", || layout_test::test_layout(tcx));
sess.time("abi_testing", || abi_test::test_abi(tcx));

2
compiler/rustc_interface/src/tests.rs
View file

@ -684,7 +684,6 @@ fn test_unstable_options_tracking_hash() {
untracked!(dep_tasks, true);
untracked!(dont_buffer_diagnostics, true);
untracked!(dump_dep_graph, true);
untracked!(dump_drop_tracking_cfg, Some("cfg.dot".to_string()));
untracked!(dump_mir, Some(String::from("abc")));
untracked!(dump_mir_dataflow, true);
untracked!(dump_mir_dir, String::from("abc"));
@ -773,7 +772,6 @@ fn test_unstable_options_tracking_hash() {
tracked!(debug_info_for_profiling, true);
tracked!(debug_macros, true);
tracked!(dep_info_omit_d_target, true);
tracked!(drop_tracking, true);
tracked!(dual_proc_macros, true);
tracked!(dwarf_version, Some(5));
tracked!(emit_thin_lto, false);

1
compiler/rustc_lint_defs/src/builtin.rs
View file

@ -306,6 +306,7 @@ declare_lint! {
/// pub async fn uhoh() {
/// let guard = SyncThing {};
/// yield_now().await;
/// let _guard = guard;
/// }
/// ```
///

19
compiler/rustc_metadata/src/rmeta/decoder.rs
View file

@ -24,7 +24,6 @@ use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
use rustc_middle::ty::codec::TyDecoder;
use rustc_middle::ty::fast_reject::SimplifiedType;
use rustc_middle::ty::GeneratorDiagnosticData;
use rustc_middle::ty::{self, ParameterizedOverTcx, Ty, TyCtxt, Visibility};
use rustc_serialize::opaque::MemDecoder;
use rustc_serialize::{Decodable, Decoder};
@ -1750,24 +1749,6 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.clone()
}
fn get_generator_diagnostic_data(
self,
tcx: TyCtxt<'tcx>,
id: DefIndex,
) -> Option<GeneratorDiagnosticData<'tcx>> {
self.root
.tables
.generator_diagnostic_data
.get(self, id)
.map(|param| param.decode((self, tcx)))
.map(|generator_data| GeneratorDiagnosticData {
generator_interior_types: generator_data.generator_interior_types,
hir_owner: generator_data.hir_owner,
nodes_types: generator_data.nodes_types,
adjustments: generator_data.adjustments,
})
}
fn get_attr_flags(self, index: DefIndex) -> AttrFlags {
self.root.tables.attr_flags.get(self, index)
}

1
compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
View file

@ -374,7 +374,6 @@ provide! { tcx, def_id, other, cdata,
crate_extern_paths => { cdata.source().paths().cloned().collect() }
expn_that_defined => { cdata.get_expn_that_defined(def_id.index, tcx.sess) }
generator_diagnostic_data => { cdata.get_generator_diagnostic_data(tcx, def_id.index) }
is_doc_hidden => { cdata.get_attr_flags(def_id.index).contains(AttrFlags::IS_DOC_HIDDEN) }
doc_link_resolutions => { tcx.arena.alloc(cdata.get_doc_link_resolutions(def_id.index)) }
doc_link_traits_in_scope => {

21
compiler/rustc_metadata/src/rmeta/encoder.rs
View file

@ -1439,7 +1439,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
}
}
if let DefKind::Generator = def_kind {
self.encode_info_for_generator(local_id);
let data = self.tcx.generator_kind(def_id).unwrap();
record!(self.tables.generator_kind[def_id] <- data);
}
if let DefKind::Enum | DefKind::Struct | DefKind::Union = def_kind {
self.encode_info_for_adt(local_id);
@ -1612,8 +1613,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
record!(self.tables.closure_saved_names_of_captured_variables[def_id.to_def_id()]
<- tcx.closure_saved_names_of_captured_variables(def_id));
if tcx.sess.opts.unstable_opts.drop_tracking_mir
&& let DefKind::Generator = self.tcx.def_kind(def_id)
if let DefKind::Generator = self.tcx.def_kind(def_id)
&& let Some(witnesses) = tcx.mir_generator_witnesses(def_id)
{
record!(self.tables.mir_generator_witnesses[def_id.to_def_id()] <- witnesses);
@ -1640,6 +1640,12 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
}
record!(self.tables.promoted_mir[def_id.to_def_id()] <- tcx.promoted_mir(def_id));
if let DefKind::Generator = self.tcx.def_kind(def_id)
&& let Some(witnesses) = tcx.mir_generator_witnesses(def_id)
{
record!(self.tables.mir_generator_witnesses[def_id.to_def_id()] <- witnesses);
}
let instance = ty::InstanceDef::Item(def_id.to_def_id());
let unused = tcx.unused_generic_params(instance);
self.tables.unused_generic_params.set(def_id.local_def_index, unused);
@ -1712,15 +1718,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
record!(self.tables.macro_definition[def_id.to_def_id()] <- &*macro_def.body);
}
#[instrument(level = "debug", skip(self))]
fn encode_info_for_generator(&mut self, def_id: LocalDefId) {
let typeck_result: &'tcx ty::TypeckResults<'tcx> = self.tcx.typeck(def_id);
let data = self.tcx.generator_kind(def_id).unwrap();
let generator_diagnostic_data = typeck_result.get_generator_diagnostic_data();
record!(self.tables.generator_kind[def_id.to_def_id()] <- data);
record!(self.tables.generator_diagnostic_data[def_id.to_def_id()] <- generator_diagnostic_data);
}
fn encode_native_libraries(&mut self) -> LazyArray<NativeLib> {
empty_proc_macro!(self);
let used_libraries = self.tcx.native_libraries(LOCAL_CRATE);

3
compiler/rustc_metadata/src/rmeta/mod.rs
View file

@ -23,7 +23,7 @@ use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
use rustc_middle::mir;
use rustc_middle::ty::fast_reject::SimplifiedType;
use rustc_middle::ty::{self, ReprOptions, Ty, UnusedGenericParams};
use rustc_middle::ty::{DeducedParamAttrs, GeneratorDiagnosticData, ParameterizedOverTcx, TyCtxt};
use rustc_middle::ty::{DeducedParamAttrs, ParameterizedOverTcx, TyCtxt};
use rustc_middle::util::Providers;
use rustc_serialize::opaque::FileEncoder;
use rustc_session::config::SymbolManglingVersion;
@ -452,7 +452,6 @@ define_tables! {
// definitions from any given crate.
def_keys: Table<DefIndex, LazyValue<DefKey>>,
proc_macro_quoted_spans: Table<usize, LazyValue<Span>>,
generator_diagnostic_data: Table<DefIndex, LazyValue<GeneratorDiagnosticData<'static>>>,
variant_data: Table<DefIndex, LazyValue<VariantData>>,
assoc_container: Table<DefIndex, ty::AssocItemContainer>,
macro_definition: Table<DefIndex, LazyValue<ast::DelimArgs>>,

7
compiler/rustc_middle/src/query/mod.rs
View file

@ -44,7 +44,6 @@ use crate::traits::{
use crate::ty::fast_reject::SimplifiedType;
use crate::ty::layout::ValidityRequirement;
use crate::ty::util::AlwaysRequiresDrop;
use crate::ty::GeneratorDiagnosticData;
use crate::ty::TyCtxtFeed;
use crate::ty::{
self, print::describe_as_module, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt,
@ -2149,12 +2148,6 @@ rustc_queries! {
desc { "computing the backend features for CLI flags" }
}
query generator_diagnostic_data(key: DefId) -> &'tcx Option<GeneratorDiagnosticData<'tcx>> {
arena_cache
desc { |tcx| "looking up generator diagnostic data of `{}`", tcx.def_path_str(key) }
separate_provide_extern
}
query check_validity_requirement(key: (ValidityRequirement, ty::ParamEnvAnd<'tcx, Ty<'tcx>>)) -> Result<bool, &'tcx ty::layout::LayoutError<'tcx>> {
desc { "checking validity requirement for `{}`: {}", key.1.value, key.0 }
}

1
compiler/rustc_middle/src/ty/codec.rs
View file

@ -566,6 +566,5 @@ impl_binder_encode_decode! {
ty::TraitPredicate<'tcx>,
ty::ExistentialPredicate<'tcx>,
ty::TraitRef<'tcx>,
Vec<ty::GeneratorInteriorTypeCause<'tcx>>,
ty::ExistentialTraitRef<'tcx>,
}

5
compiler/rustc_middle/src/ty/mod.rs
View file

@ -106,9 +106,8 @@ pub use self::sty::{
};
pub use self::trait_def::TraitDef;
pub use self::typeck_results::{
CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
GeneratorDiagnosticData, GeneratorInteriorTypeCause, TypeckResults, UserType,
UserTypeAnnotationIndex,
CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, TypeckResults,
UserType, UserTypeAnnotationIndex,
};
pub mod _match;

1
compiler/rustc_middle/src/ty/parameterized.rs
View file

@ -132,5 +132,4 @@ parameterized_over_tcx! {
ty::Predicate,
ty::Clause,
ty::ClauseKind,
ty::GeneratorDiagnosticData,
}

70
compiler/rustc_middle/src/ty/typeck_results.rs
View file

@ -189,10 +189,6 @@ pub struct TypeckResults<'tcx> {
/// Details may be find in `rustc_hir_analysis::check::rvalue_scopes`.
pub rvalue_scopes: RvalueScopes,
/// Stores the type, expression, span and optional scope span of all types
/// that are live across the yield of this generator (if a generator).
pub generator_interior_types: ty::Binder<'tcx, Vec<GeneratorInteriorTypeCause<'tcx>>>,
/// Stores the predicates that apply on generator witness types.
/// formatting modified file tests/ui/generator/retain-resume-ref.rs
pub generator_interior_predicates:
@ -212,49 +208,6 @@ pub struct TypeckResults<'tcx> {
offset_of_data: ItemLocalMap<(Ty<'tcx>, Vec<FieldIdx>)>,
}
/// Whenever a value may be live across a generator yield, the type of that value winds up in the
/// `GeneratorInteriorTypeCause` struct. This struct adds additional information about such
/// captured types that can be useful for diagnostics. In particular, it stores the span that
/// caused a given type to be recorded, along with the scope that enclosed the value (which can
/// be used to find the await that the value is live across).
///
/// For example:
///
/// ```ignore (pseudo-Rust)
/// async move {
/// let x: T = expr;
/// foo.await
/// ...
/// }
/// ```
///
/// Here, we would store the type `T`, the span of the value `x`, the "scope-span" for
/// the scope that contains `x`, the expr `T` evaluated from, and the span of `foo.await`.
#[derive(TyEncodable, TyDecodable, Clone, Debug, Eq, Hash, PartialEq, HashStable)]
#[derive(TypeFoldable, TypeVisitable)]
pub struct GeneratorInteriorTypeCause<'tcx> {
/// Type of the captured binding.
pub ty: Ty<'tcx>,
/// Span of the binding that was captured.
pub span: Span,
/// Span of the scope of the captured binding.
pub scope_span: Option<Span>,
/// Span of `.await` or `yield` expression.
pub yield_span: Span,
/// Expr which the type evaluated from.
pub expr: Option<hir::HirId>,
}
// This type holds diagnostic information on generators and async functions across crate boundaries
// and is used to provide better error messages
#[derive(TyEncodable, TyDecodable, Clone, Debug, HashStable)]
pub struct GeneratorDiagnosticData<'tcx> {
pub generator_interior_types: ty::Binder<'tcx, Vec<GeneratorInteriorTypeCause<'tcx>>>,
pub hir_owner: DefId,
pub nodes_types: ItemLocalMap<Ty<'tcx>>,
pub adjustments: ItemLocalMap<Vec<ty::adjustment::Adjustment<'tcx>>>,
}
impl<'tcx> TypeckResults<'tcx> {
pub fn new(hir_owner: OwnerId) -> TypeckResults<'tcx> {
TypeckResults {
@ -278,7 +231,6 @@ impl<'tcx> TypeckResults<'tcx> {
closure_min_captures: Default::default(),
closure_fake_reads: Default::default(),
rvalue_scopes: Default::default(),
generator_interior_types: ty::Binder::dummy(Default::default()),
generator_interior_predicates: Default::default(),
treat_byte_string_as_slice: Default::default(),
closure_size_eval: Default::default(),
@ -351,28 +303,6 @@ impl<'tcx> TypeckResults<'tcx> {
LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.node_types }
}
pub fn get_generator_diagnostic_data(&self) -> GeneratorDiagnosticData<'tcx> {
let generator_interior_type = self.generator_interior_types.map_bound_ref(|vec| {
vec.iter()
.map(|item| {
GeneratorInteriorTypeCause {
ty: item.ty,
span: item.span,
scope_span: item.scope_span,
yield_span: item.yield_span,
expr: None, //FIXME: Passing expression over crate boundaries is impossible at the moment
}
})
.collect::<Vec<_>>()
});
GeneratorDiagnosticData {
generator_interior_types: generator_interior_type,
hir_owner: self.hir_owner.to_def_id(),
nodes_types: self.node_types.clone(),
adjustments: self.adjustments.clone(),
}
}
pub fn node_type(&self, id: hir::HirId) -> Ty<'tcx> {
self.node_type_opt(id).unwrap_or_else(|| {
bug!("node_type: no type for node {}", tls::with(|tcx| tcx.hir().node_to_string(id)))

83
compiler/rustc_mir_transform/src/generator.rs
View file

@ -853,60 +853,7 @@ impl StorageConflictVisitor<'_, '_, '_> {
}
}
/// Validates the typeck view of the generator against the actual set of types saved between
/// yield points.
fn sanitize_witness<'tcx>(
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
witness: Ty<'tcx>,
upvars: &'tcx ty::List<Ty<'tcx>>,
layout: &GeneratorLayout<'tcx>,
) {
let did = body.source.def_id();
let param_env = tcx.param_env(did);
let allowed_upvars = tcx.normalize_erasing_regions(param_env, upvars);
let allowed = match witness.kind() {
&ty::GeneratorWitness(interior_tys) => {
tcx.normalize_erasing_late_bound_regions(param_env, interior_tys)
}
_ => {
tcx.sess.delay_span_bug(
body.span,
format!("unexpected generator witness type {:?}", witness.kind()),
);
return;
}
};
let mut mismatches = Vec::new();
for fty in &layout.field_tys {
if fty.ignore_for_traits {
continue;
}
let decl_ty = tcx.normalize_erasing_regions(param_env, fty.ty);
// Sanity check that typeck knows about the type of locals which are
// live across a suspension point
if !allowed.contains(&decl_ty) && !allowed_upvars.contains(&decl_ty) {
mismatches.push(decl_ty);
}
}
if !mismatches.is_empty() {
span_bug!(
body.span,
"Broken MIR: generator contains type {:?} in MIR, \
but typeck only knows about {} and {:?}",
mismatches,
allowed,
allowed_upvars
);
}
}
fn compute_layout<'tcx>(
tcx: TyCtxt<'tcx>,
liveness: LivenessInfo,
body: &Body<'tcx>,
) -> (
@ -932,12 +879,11 @@ fn compute_layout<'tcx>(
let decl = &body.local_decls[local];
debug!(?decl);
let ignore_for_traits = if tcx.sess.opts.unstable_opts.drop_tracking_mir {
// Do not `assert_crate_local` here, as post-borrowck cleanup may have already cleared
// the information. This is alright, since `ignore_for_traits` is only relevant when
// this code runs on pre-cleanup MIR, and `ignore_for_traits = false` is the safer
// default.
match decl.local_info {
let ignore_for_traits = match decl.local_info {
// Do not include raw pointers created from accessing `static` items, as those could
// well be re-created by another access to the same static.
ClearCrossCrate::Set(box LocalInfo::StaticRef { is_thread_local, .. }) => {
@ -947,12 +893,6 @@ fn compute_layout<'tcx>(
// post-analysis MIR.
ClearCrossCrate::Set(box LocalInfo::FakeBorrow) => true,
_ => false,
}
} else {
// FIXME(#105084) HIR-based drop tracking does not account for all the temporaries that
// MIR building may introduce. This leads to wrongly ignored types, but this is
// necessary for internal consistency and to avoid ICEs.
decl.internal
};
let decl =
GeneratorSavedTy { ty: decl.ty, source_info: decl.source_info, ignore_for_traits };
@ -1445,8 +1385,6 @@ pub(crate) fn mir_generator_witnesses<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: LocalDefId,
) -> Option<GeneratorLayout<'tcx>> {
assert!(tcx.sess.opts.unstable_opts.drop_tracking_mir);
let (body, _) = tcx.mir_promoted(def_id);
let body = body.borrow();
let body = &*body;
@ -1469,7 +1407,7 @@ pub(crate) fn mir_generator_witnesses<'tcx>(
// Extract locals which are live across suspension point into `layout`
// `remap` gives a mapping from local indices onto generator struct indices
// `storage_liveness` tells us which locals have live storage at suspension points
let (_, generator_layout, _) = compute_layout(tcx, liveness_info, body);
let (_, generator_layout, _) = compute_layout(liveness_info, body);
check_suspend_tys(tcx, &generator_layout, &body);
@ -1489,15 +1427,10 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
let gen_ty = body.local_decls.raw[1].ty;
// Get the discriminant type and args which typeck computed
let (discr_ty, upvars, interior, movable) = match *gen_ty.kind() {
let (discr_ty, movable) = match *gen_ty.kind() {
ty::Generator(_, args, movability) => {
let args = args.as_generator();
(
args.discr_ty(tcx),
args.upvar_tys(),
args.witness(),
movability == hir::Movability::Movable,
)
(args.discr_ty(tcx), movability == hir::Movability::Movable)
}
_ => {
tcx.sess.delay_span_bug(body.span, format!("unexpected generator type {gen_ty}"));
@ -1574,13 +1507,7 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
// Extract locals which are live across suspension point into `layout`
// `remap` gives a mapping from local indices onto generator struct indices
// `storage_liveness` tells us which locals have live storage at suspension points
let (remap, layout, storage_liveness) = compute_layout(tcx, liveness_info, body);
if tcx.sess.opts.unstable_opts.validate_mir
&& !tcx.sess.opts.unstable_opts.drop_tracking_mir
{
sanitize_witness(tcx, body, interior, upvars, &layout);
}
let (remap, layout, storage_liveness) = compute_layout(liveness_info, body);
let can_return = can_return(tcx, body, tcx.param_env(body.source.def_id()));

4
compiler/rustc_mir_transform/src/lib.rs
View file

@ -358,9 +358,7 @@ fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: LocalDefId) -> Body<'_> {
/// mir borrowck *before* doing so in order to ensure that borrowck can be run and doesn't
/// end up missing the source MIR due to stealing happening.
fn mir_drops_elaborated_and_const_checked(tcx: TyCtxt<'_>, def: LocalDefId) -> &Steal<Body<'_>> {
if tcx.sess.opts.unstable_opts.drop_tracking_mir
&& let DefKind::Generator = tcx.def_kind(def)
{
if let DefKind::Generator = tcx.def_kind(def) {
tcx.ensure_with_value().mir_generator_witnesses(def);
}
let mir_borrowck = tcx.mir_borrowck(def);

6
compiler/rustc_session/src/options.rs
View file

@ -1458,17 +1458,11 @@ options! {
dont_buffer_diagnostics: bool = (false, parse_bool, [UNTRACKED],
"emit diagnostics rather than buffering (breaks NLL error downgrading, sorting) \
(default: no)"),
drop_tracking: bool = (false, parse_bool, [TRACKED],
"enables drop tracking in generators (default: no)"),
drop_tracking_mir: bool = (false, parse_bool, [TRACKED],
"enables drop tracking on MIR in generators (default: no)"),
dual_proc_macros: bool = (false, parse_bool, [TRACKED],
"load proc macros for both target and host, but only link to the target (default: no)"),
dump_dep_graph: bool = (false, parse_bool, [UNTRACKED],
"dump the dependency graph to $RUST_DEP_GRAPH (default: /tmp/dep_graph.gv) \
(default: no)"),
dump_drop_tracking_cfg: Option<String> = (None, parse_opt_string, [UNTRACKED],
"dump drop-tracking control-flow graph as a `.dot` file (default: no)"),
dump_mir: Option<String> = (None, parse_opt_string, [UNTRACKED],
"dump MIR state to file.
`val` is used to select which passes and functions to dump. For example:

8
compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
View file

@ -779,6 +779,7 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
| ty::Str
| ty::Never
| ty::Foreign(..)
| ty::GeneratorWitnessMIR(..)
| ty::GeneratorWitness(..) => {}
ty::Bool => {
@ -973,12 +974,7 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
);
}
ty::Bound(..)
| ty::Error(..)
| ty::GeneratorWitnessMIR(..)
| ty::Infer(..)
| ty::Param(..)
| ty::Placeholder(..) => {
ty::Bound(..) | ty::Error(..) | ty::Infer(..) | ty::Param(..) | ty::Placeholder(..) => {
bug!("transform_ty: unexpected `{:?}`", ty.kind());
}
}

151
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -30,10 +30,9 @@ use rustc_infer::infer::{DefineOpaqueTypes, InferOk, LateBoundRegionConversionTi
use rustc_middle::hir::map;
use rustc_middle::ty::error::TypeError::{self, Sorts};
use rustc_middle::ty::{
self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind,
GeneratorDiagnosticData, GeneratorInteriorTypeCause, GenericArgs, InferTy, IsSuggestable,
ToPredicate, Ty, TyCtxt, TypeAndMut, TypeFoldable, TypeFolder, TypeSuperFoldable,
TypeVisitableExt, TypeckResults,
self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind, GenericArgs,
InferTy, IsSuggestable, ToPredicate, Ty, TyCtxt, TypeAndMut, TypeFoldable, TypeFolder,
TypeSuperFoldable, TypeVisitableExt, TypeckResults,
};
use rustc_span::def_id::LocalDefId;
use rustc_span::symbol::{sym, Ident, Symbol};
@ -58,15 +57,12 @@ pub enum GeneratorInteriorOrUpvar {
// This type provides a uniform interface to retrieve data on generators, whether it originated from
// the local crate being compiled or from a foreign crate.
#[derive(Debug)]
pub enum GeneratorData<'tcx, 'a> {
Local(&'a TypeckResults<'tcx>),
Foreign(&'tcx GeneratorDiagnosticData<'tcx>),
}
struct GeneratorData<'tcx, 'a>(&'a TypeckResults<'tcx>);
impl<'tcx, 'a> GeneratorData<'tcx, 'a> {
// Try to get information about variables captured by the generator that matches a type we are
// looking for with `ty_matches` function. We uses it to find upvar which causes a failure to
// meet an obligation
/// Try to get information about variables captured by the generator that matches a type we are
/// looking for with `ty_matches` function. We uses it to find upvar which causes a failure to
/// meet an obligation
fn try_get_upvar_span<F>(
&self,
infer_context: &InferCtxt<'tcx>,
@ -76,27 +72,21 @@ impl<'tcx, 'a> GeneratorData<'tcx, 'a> {
where
F: Fn(ty::Binder<'tcx, Ty<'tcx>>) -> bool,
{
match self {
GeneratorData::Local(typeck_results) => {
infer_context.tcx.upvars_mentioned(generator_did).and_then(|upvars| {
upvars.iter().find_map(|(upvar_id, upvar)| {
let upvar_ty = typeck_results.node_type(*upvar_id);
let upvar_ty = self.0.node_type(*upvar_id);
let upvar_ty = infer_context.resolve_vars_if_possible(upvar_ty);
ty_matches(ty::Binder::dummy(upvar_ty))
.then(|| GeneratorInteriorOrUpvar::Upvar(upvar.span))
})
})
}
GeneratorData::Foreign(_) => None,
}
}
// Try to get the span of a type being awaited on that matches the type we are looking with the
// `ty_matches` function. We uses it to find awaited type which causes a failure to meet an
// obligation
/// Try to get the span of a type being awaited on that matches the type we are looking with the
/// `ty_matches` function. We uses it to find awaited type which causes a failure to meet an
/// obligation
fn get_from_await_ty<F>(
&self,
tcx: TyCtxt<'tcx>,
visitor: AwaitsVisitor,
hir: map::Map<'tcx>,
ty_matches: F,
@ -104,69 +94,12 @@ impl<'tcx, 'a> GeneratorData<'tcx, 'a> {
where
F: Fn(ty::Binder<'tcx, Ty<'tcx>>) -> bool,
{
match self {
GeneratorData::Local(typeck_results) => visitor
visitor
.awaits
.into_iter()
.map(|id| hir.expect_expr(id))
.find(|await_expr| {
ty_matches(ty::Binder::dummy(typeck_results.expr_ty_adjusted(&await_expr)))
})
.map(|expr| expr.span),
GeneratorData::Foreign(generator_diagnostic_data) => visitor
.awaits
.into_iter()
.map(|id| hir.expect_expr(id))
.find(|await_expr| {
ty_matches(ty::Binder::dummy(
generator_diagnostic_data
.adjustments
.get(&await_expr.hir_id.local_id)
.map_or::<&[ty::adjustment::Adjustment<'tcx>], _>(&[], |a| &a[..])
.last()
.map_or_else::<Ty<'tcx>, _, _>(
|| {
generator_diagnostic_data
.nodes_types
.get(&await_expr.hir_id.local_id)
.cloned()
.unwrap_or_else(|| {
bug!(
"node_type: no type for node {}",
tcx.hir().node_to_string(await_expr.hir_id)
)
})
},
|adj| adj.target,
),
))
})
.map(|expr| expr.span),
}
}
/// Get the type, expression, span and optional scope span of all types
/// that are live across the yield of this generator
fn get_generator_interior_types(
&self,
) -> ty::Binder<'tcx, &[GeneratorInteriorTypeCause<'tcx>]> {
match self {
GeneratorData::Local(typeck_result) => {
typeck_result.generator_interior_types.as_deref()
}
GeneratorData::Foreign(generator_diagnostic_data) => {
generator_diagnostic_data.generator_interior_types.as_deref()
}
}
}
// Used to get the source of the data, note we don't have as much information for generators
// originated from foreign crates
fn is_foreign(&self) -> bool {
match self {
GeneratorData::Local(_) => false,
GeneratorData::Foreign(_) => true,
}
.find(|await_expr| ty_matches(ty::Binder::dummy(self.0.expr_ty_adjusted(&await_expr))))
.map(|expr| expr.span)
}
}
@ -316,7 +249,7 @@ pub trait TypeErrCtxtExt<'tcx> {
outer_generator: Option<DefId>,
trait_pred: ty::TraitPredicate<'tcx>,
target_ty: Ty<'tcx>,
typeck_results: Option<&ty::TypeckResults<'tcx>>,
typeck_results: &ty::TypeckResults<'tcx>,
obligation: &PredicateObligation<'tcx>,
next_code: Option<&ObligationCauseCode<'tcx>>,
);
@ -2351,12 +2284,9 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
// cycles. If we can't use resolved types because the generator comes from another crate,
// we still provide a targeted error but without all the relevant spans.
let generator_data = match &self.typeck_results {
Some(t) if t.hir_owner.to_def_id() == generator_did_root => GeneratorData::Local(&t),
Some(t) if t.hir_owner.to_def_id() == generator_did_root => GeneratorData(&t),
_ if generator_did.is_local() => {
GeneratorData::Local(self.tcx.typeck(generator_did.expect_local()))
}
_ if let Some(generator_diag_data) = self.tcx.generator_diagnostic_data(generator_did) => {
GeneratorData::Foreign(generator_diag_data)
GeneratorData(self.tcx.typeck(generator_did.expect_local()))
}
_ => return false,
};
@ -2368,30 +2298,11 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
let mut interior_or_upvar_span = None;
let from_awaited_ty = generator_data.get_from_await_ty(self.tcx, visitor, hir, ty_matches);
let from_awaited_ty = generator_data.get_from_await_ty(visitor, hir, ty_matches);
debug!(?from_awaited_ty);
// The generator interior types share the same binders
if let Some(cause) =
generator_data.get_generator_interior_types().skip_binder().iter().find(
|ty::GeneratorInteriorTypeCause { ty, .. }| {
ty_matches(generator_data.get_generator_interior_types().rebind(*ty))
},
)
{
let ty::GeneratorInteriorTypeCause { span, scope_span, yield_span, expr, .. } = cause;
interior_or_upvar_span = Some(GeneratorInteriorOrUpvar::Interior(
*span,
Some((*scope_span, *yield_span, *expr, from_awaited_ty)),
));
if interior_or_upvar_span.is_none() && generator_data.is_foreign() {
interior_or_upvar_span = Some(GeneratorInteriorOrUpvar::Interior(*span, None));
}
} else if self.tcx.sess.opts.unstable_opts.drop_tracking_mir
// Avoid disclosing internal information to downstream crates.
&& generator_did.is_local()
if generator_did.is_local()
// Try to avoid cycles.
&& !generator_within_in_progress_typeck
&& let Some(generator_info) = self.tcx.mir_generator_witnesses(generator_did)
@ -2420,17 +2331,14 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
generator_data.try_get_upvar_span(&self, generator_did, ty_matches);
}
if interior_or_upvar_span.is_none() && generator_data.is_foreign() {
if interior_or_upvar_span.is_none() && !generator_did.is_local() {
interior_or_upvar_span = Some(GeneratorInteriorOrUpvar::Interior(span, None));
}
debug!(?interior_or_upvar_span);
if let Some(interior_or_upvar_span) = interior_or_upvar_span {
let is_async = self.tcx.generator_is_async(generator_did);
let typeck_results = match generator_data {
GeneratorData::Local(typeck_results) => Some(typeck_results),
GeneratorData::Foreign(_) => None,
};
let typeck_results = generator_data.0;
self.note_obligation_cause_for_async_await(
err,
interior_or_upvar_span,
@ -2459,7 +2367,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
outer_generator: Option<DefId>,
trait_pred: ty::TraitPredicate<'tcx>,
target_ty: Ty<'tcx>,
typeck_results: Option<&ty::TypeckResults<'tcx>>,
typeck_results: &ty::TypeckResults<'tcx>,
obligation: &PredicateObligation<'tcx>,
next_code: Option<&ObligationCauseCode<'tcx>>,
) {
@ -2584,11 +2492,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
);
} else {
// Look at the last interior type to get a span for the `.await`.
debug!(
generator_interior_types = ?format_args!(
"{:#?}", typeck_results.as_ref().map(|t| &t.generator_interior_types)
),
);
explain_yield(interior_span, yield_span, scope_span);
}
@ -2608,14 +2511,10 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
// ^^^^^^^ a temporary `&T` created inside this method call due to `&self`
// ```
//
let is_region_borrow = if let Some(typeck_results) = typeck_results {
typeck_results
let is_region_borrow = typeck_results
.expr_adjustments(expr)
.iter()
.any(|adj| adj.is_region_borrow())
} else {
false
};
.any(|adj| adj.is_region_borrow());
// ```rust
// struct Foo(*const u8);
@ -2628,7 +2527,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
DefKind::Fn | DefKind::Ctor(..) => target_ty.is_unsafe_ptr(),
_ => false,
};
if let Some(typeck_results) = typeck_results {
if (typeck_results.is_method_call(e) && is_region_borrow)
|| is_raw_borrow_inside_fn_like_call
{
@ -2642,7 +2540,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
}
}
}
}
GeneratorInteriorOrUpvar::Upvar(upvar_span) => {
// `Some((ref_ty, is_mut))` if `target_ty` is `&T` or `&mut T` and fails to impl `Send`
let non_send = match target_ty.kind() {

27
compiler/rustc_ty_utils/src/needs_drop.rs
View file

@ -7,7 +7,7 @@ use rustc_middle::ty::util::{needs_drop_components, AlwaysRequiresDrop};
use rustc_middle::ty::GenericArgsRef;
use rustc_middle::ty::{self, EarlyBinder, Ty, TyCtxt};
use rustc_session::Limit;
use rustc_span::{sym, DUMMY_SP};
use rustc_span::sym;
use crate::errors::NeedsDropOverflow;
@ -133,7 +133,7 @@ where
// The information required to determine whether a generator has drop is
// computed on MIR, while this very method is used to build MIR.
// To avoid cycles, we consider that generators always require drop.
ty::Generator(..) if tcx.sess.opts.unstable_opts.drop_tracking_mir => {
ty::Generator(..) => {
return Some(Err(AlwaysRequiresDrop));
}
@ -145,29 +145,6 @@ where
}
}
ty::Generator(def_id, args, _) => {
let args = args.as_generator();
for upvar in args.upvar_tys() {
queue_type(self, upvar);
}
let witness = args.witness();
let interior_tys = match witness.kind() {
&ty::GeneratorWitness(tys) => tcx.erase_late_bound_regions(tys),
_ => {
tcx.sess.delay_span_bug(
tcx.hir().span_if_local(def_id).unwrap_or(DUMMY_SP),
format!("unexpected generator witness type {witness:?}"),
);
return Some(Err(AlwaysRequiresDrop));
}
};
for interior_ty in interior_tys {
queue_type(self, interior_ty);
}
}
// Check for a `Drop` impl and whether this is a union or
// `ManuallyDrop`. If it's a struct or enum without a `Drop`
// impl then check whether the field types need `Drop`.

43
src/tools/clippy/clippy_lints/src/await_holding_invalid.rs
View file

@ -2,9 +2,9 @@ use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::{match_def_path, paths};
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def_id::DefId;
use rustc_hir::{AsyncGeneratorKind, Body, BodyId, GeneratorKind};
use rustc_hir::{AsyncGeneratorKind, Body, GeneratorKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::GeneratorInteriorTypeCause;
use rustc_middle::mir::GeneratorLayout;
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::{sym, Span};
@ -197,28 +197,35 @@ impl LateLintPass<'_> for AwaitHolding {
fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
use AsyncGeneratorKind::{Block, Closure, Fn};
if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
let body_id = BodyId {
hir_id: body.value.hir_id,
};
let typeck_results = cx.tcx.typeck_body(body_id);
self.check_interior_types(
cx,
typeck_results.generator_interior_types.as_ref().skip_binder(),
body.value.span,
);
let def_id = cx.tcx.hir().body_owner_def_id(body.id());
if let Some(generator_layout) = cx.tcx.mir_generator_witnesses(def_id) {
self.check_interior_types(cx, generator_layout);
}
}
}
}
impl AwaitHolding {
fn check_interior_types(&self, cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
for ty_cause in ty_causes {
fn check_interior_types(&self, cx: &LateContext<'_>, generator: &GeneratorLayout<'_>) {
for (ty_index, ty_cause) in generator.field_tys.iter_enumerated() {
if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
let await_points = || {
generator
.variant_source_info
.iter_enumerated()
.filter_map(|(variant, source_info)| {
generator.variant_fields[variant]
.raw
.contains(&ty_index)
.then_some(source_info.span)
})
.collect::<Vec<_>>()
};
if is_mutex_guard(cx, adt.did()) {
span_lint_and_then(
cx,
AWAIT_HOLDING_LOCK,
ty_cause.span,
ty_cause.source_info.span,
"this `MutexGuard` is held across an `await` point",
|diag| {
diag.help(
@ -226,7 +233,7 @@ impl AwaitHolding {
`MutexGuard` is dropped before calling await",
);
diag.span_note(
ty_cause.scope_span.unwrap_or(span),
await_points(),
"these are all the `await` points this lock is held through",
);
},
@ -235,18 +242,18 @@ impl AwaitHolding {
span_lint_and_then(
cx,
AWAIT_HOLDING_REFCELL_REF,
ty_cause.span,
ty_cause.source_info.span,
"this `RefCell` reference is held across an `await` point",
|diag| {
diag.help("ensure the reference is dropped before calling `await`");
diag.span_note(
ty_cause.scope_span.unwrap_or(span),
await_points(),
"these are all the `await` points this reference is held through",
);
},
);
} else if let Some(disallowed) = self.def_ids.get(&adt.did()) {
emit_invalid_type(cx, ty_cause.span, disallowed);
emit_invalid_type(cx, ty_cause.source_info.span, disallowed);
}
}
}